Principles of Biomedical ScienceEnd of Course ReviewPBS Activity Introductions

Activity 1.1.1: The Mystery—Was It a Crime?

Introduction

The biomedical sciences are involved in a variety of aspects of modern society including but not limited to research, medicine, health care, pharmacology, medical technology, and even forensics. Throughout this course, you will have a chance to explore many of these areas and the career opportunities within them.

To begin your work, you find yourself in the middle of a mystery. In Unit One it is your job to solve the mystery of a sudden death. The biomedical sciences are directly involved in all aspects of life including what can cause life to end. Forensic science is a popular field within the biomedical sciences that has been made increasingly fashionable by several television shows with crime solving and forensic themes, especially the CSI series. Forensic science sometimes focuses on tracking down the causes of cell injury, illness and death.

The starting point of any work in the biomedical sciences must be the human body. A working knowledge of its structure and function is basic to an understanding of all other aspects of this interesting discipline. In Lesson One you will begin a journey of exploration into how the body functions. You will explore the several interdependent systems that together make up the human body.

When something happens to a system to cause a malfunction, it can have minor or very serious implications for the whole body. Such is the case in our mystery. The story begins by reading the paragraph below.

In this activity, you will read for content and identify important pieces of information that may be clues to the mysterious death of a woman.

The Mystery!

It was a warm, summer morning. The emergency call came in at 7:15 am. The 911 operator notified the local police and the emergency medical technicians (EMT). Both the police and the EMT arrived at the scene at 7:26 am. The front door was ajar and a woman lay face down in the entry hallway. She appeared to be in her mid-thirties and of Hispanic descent. Next to the body was a small table that had been knocked over. Blood stains were on the edge of the table and under the head of the victim. Trauma to the head was clearly evident. The victim had vomited and her fingernails were gray. She had been found by a neighbor who was alerted by the loud, excited barking of the victim’s dog in this normally quiet suburban neighborhood. The EMT determined the woman was dead. The police notified the crime scene investigators and the coroner who were dispatched to the house. The neighbor informed the police that she had spoken to the victim when she saw her walking her dog around 6:30 am that morning. The neighbor said the victim routinely walked her dog each morning at that time and that she appeared to be fine when they talked that morning. After the crime scene investigators finished examining the home, the coroner removed the body and took it to the medical examiner’s office for evaluation to determine the cause of death.

Was the death by natural causes or had a crime been committed? The mystery begins. (Don’t worry – the dog was taken to the home of close family friends and is doing just fine!)

Activity 1.1.3: How Do the Parts Make a Whole?

Introduction

A woman in her mid-thirties died; that means that at least one of her body systems was no longer able to support life. The failure of her body systems to support life may be the result of injury due to an accident or a crime, or it could be the result of an illness. Before we can determine which system or systems failed or what caused the failure which led to her death, we have to learn more about the human body.

The human body has been the focus of many very interesting, entertaining and action packed science fiction movies and books. Superman, the bionic woman, the Terminator, and Frankenstein are just a few examples of imaginary humans with super powers! It’s fun to think of the possibilities! How out of the realm of reality are these possibilities? With the ever changing world of biomedical science, will there come a time when we can actually build a living machine? Already it is possible to replace worn out parts with new ones including artificial limbs, joints, and hearts. But, what about replacing entire systems? Can you imagine an artificial cardiovascular system, for example? What would replacing a system really involve? To even consider the possibility, you must understand what a system is and what it does.

The human body is composed of several interrelated systems which are in turn composed of cells, tissues and organs that act independently and interdependently within the body. Each of these components acts as part of a given system that interacts with other systems to provide the metabolic processes needed to maintain life.

Organs are composed of tissues that in turn are made from cells. Cells and tissues of different organs within a body system are highly specialized and have very different structures and functions. Even with that specialization there are specific structures and necessary functions that are common to all living tissues and cells.

The human body is a complex living machine that depends upon many interactions to maintain your good health.

Activity 1.1.4: What Is Our Skeletal System?

Introduction

In Activity 1.1.3, you and your classmates investigated several body systems that function to sustain life, including digestive, cardiovascular, and respiratory. The system that protects and physically supports each of these systems is the skeletal system. The human skeleton has become an

icon for horror films and Halloween. It is easily recognized by the youngest child, yet few people understand its importance to sustain life. Think about how you would look and move if you did not have any bones. You would only be a few inches tall!

The skeleton is not only a rigid framework for muscle attachment. It also protects the soft tissues and organs, and stores and releases minerals; the red bone marrow inside many bones is the origin of all blood cells. Have you ever broken a bone? If you have, then you know the bone has many nerve endings and that it can repair itself. Bone tissue even stores fats! So the bones are not just rigid rods or pipes; they have many functions necessary for sustaining life.

Each component in the skeletal system interacts or is connected to every other component. Remember the children’s song that includes the lyrics The ankle bone is connected to the leg bone, and the leg bone is connected to the hip bone? Those connections are true and there are many more complex interactions between the components of the skeletal system.

You will use a strategy called concept mapping to begin exploring the links that exist between the parts of the skeletal system. A concept map is a diagram that visually represents the connections between ideas, concepts, or items. The concepts or items are connected by labeled arrows; the words on the arrows clarify the connections between the items. Because concept maps are good learning tools, you may find it very helpful to use them throughout this course to visualize ideas and to make connections. In this activity, you will follow directions to learn how to use the Inspiration® software and at the same time learn about the skeletal system as you make a concept map.

Activity 1.1.5: How Do Systems Interconnect?

Introduction

As you saw in Activity 1.1.3 the human body is composed of several different systems including nervous, endocrine, digestive, and respiratory to name just a few. Each of the systems functions to keep us alive and healthy. Think about the connections between the systems that the class drew on the body poster. Was it difficult to determine or identify those connections?

The human body is a system, made of multiple interacting systems. No individual component of a human body system works alone. Components of each system in the body affect or interact with every other system. Building a human body system that has the ability to communicate with all of its sub-systems and component parts would be quite an accomplishment. It would be a “living” machine!

This may sound like science fiction; however, advances in computer technology are producing almost human-like robots. Several researchers are working on robots that can even express human emotions. These robots must sense their environment and send signals to move their hands, feet, and face-like features. We often take for granted that we can sense our environment using our eyes, ears, and sense of touch and that we can then respond by having our brains send messages to our muscles so we can smile, walk away, or speak. For this process to occur the nervous, skeletal, and muscular systems must all interact with each other. To get an idea of the complexity of programming and mechanical design necessary for a robot to interact with its environment, take a look at an article describing the development of robots that can express multiple emotions written by the researchers at the Takanishi Laboratory at Waseda University in Japan. The article is titled “Emotion Expression Humanoid Robot WE-4RII (Waseda Eye No.4 Refined II)” and can be accessed at: http://www.takanishi.mech.waseda.ac.jp/top/research/we/we-4rII/index.htm.

For the human body to function, different systems have to work together. Every system in the body relates to every other. Consider how the oxygen obtained by the respiratory system is distributed throughout the body by the red blood cells of the circulatory system that were produced by the skeletal system!

In this activity you will investigate the interactions between two systems, practice using Inspiration® software to make outlines, and continue to develop your skills at concept mapping.

Activity 1.1.6: What Does the Evidence Say?

Introduction

Problems with one body system can have minor, moderate or very serious effects on other systems. Medical professionals often do not have an easy time understanding why changes in our bodies happen, even though modern medical technology has made huge strides in understanding the physiological changes that occur due to disease, aging, genetics, and the use of pharmaceuticals. As you continue to work towards an answer to what caused the death of the victim, a strategy is needed to organize the information. In diagnosing a problem or determining cause of death, there are often many pieces of information that must be linked together before a conclusion can be reached. In this activity, you will begin using a strategy called an evidence board, to help organize information that leads to a final determination of what killed our victim.

When a mysterious death occurs an autopsy is required. Those of you who watch the television shows CSI or NCIS are familiar with this procedure. An autopsy is a systematic examination of the entire body to determine the cause of death. It often involves extensive analysis of the tissues and body fluids and a determination if chemicals or toxins are present.

To begin Activity 1.1.6, you will watch an interactive slide show with information about autopsies. Then you will watch a video of Dr. Jan C. Garavaglia, (aka "Dr. G"), the chief medical examiner for the District Nine (Orange-Osceola) Medical Examiner's Office in Florida, describing the

tools used for an autopsy.

Activity 1.1.7: Why Confidentiality?

Introduction

Previously in this unit you investigated the responsibilities involved in the following professions:o Emergency Medical Techniciano 911 Operatoro Coroner

Each of these careers has responsibilities specific to that profession. These careers also have something very important in common. Each involves information about other people that must remain confidential. Confidentiality laws and codes of conduct in relationship to confidentiality are very important components of most careers in the medical field, not just those careers listed above.

You may have a family physician that has been monitoring your health since you were very young. Or, you may use a health center with several physicians and health personnel that have access to your personal health information. This information is very important; however it is also sensitive and most people want their medical information to remain private with limited access by other people. In 1996, the federal government passed the Health Insurance Portability and Accountability Act, known as HIPAA. HIPAA is a comprehensive set of standards and practices designed to give patients specific rights regarding their personal health information.

Consider the careers above and the information these people have access to while performing their jobs. There are multiple laws and standards (including the HIPAA regulations) designed to protect the privacy of medical information and to regulate the behavior of medical personnel who have access to medical information or witnessed medical procedures. Medical personnel who do not follow these regulations are subject to serious fines, loss of employment, and even criminal prosecution.

In this activity, you will consider the importance of confidentiality, laws that relate to it, and why it is such an important responsibility for people working with patients.

Activity 2.1.1: What Is a Pump?

Introduction

The human heart is a pump and you read in Unit 1, when the heart stops a person can die unless the heart is restarted or some intervention is used to pump blood to the tissues. That is why Anna Garcia died; her heart stopped pumping, consequently blood stopped flowing through her body. Lacking the resources normally carried by the blood, including oxygen and nutrients, Ms. Garcia’s body cells could no long survive and she died.

As you learned in Unit One, the cardiovascular system provides your body’s cells the resources needed for life and provides a transport system to get rid of waste. The most important component of this system is the muscular, four-chambered pump called the human heart. Before you begin a close examination of a heart, it is important to develop a general understanding of what a pump is and how it functions.

How many pumps do you have in or around your home? How often do you depend on them? Do you even know? The answer is probably more than 10!Think of the many substances you use on a daily basis that are in some way related to pumps: water faucet, toilet, the washing machine, the car, the air conditioner, the refrigerator, liquid soap dispensers, spray bottles, and many others. Pumps are a machine we tend to take for granted.

Think of three examples of pumps you might consider amazing because of the work each accomplishes. One example might be a pump that supplies a water tower with the water for an area of a town. Another example might be the pump on a fire truck that can pump water many stories high to fight a fire in a high rise building. The most important pump in your life is a living pump, your heart. During an average lifetime, the heart pumps over 55 million gallons of blood through a human body.

In this activity, you and a partner will build a simple pump to move 150 mL of water from one flask to a second flask that is elevated.

Activity 2.2.1: How Many Chambers Does It Have?

Introduction

The human heart is an amazing pump. Have you ever calculated how many times a day your heart beats? Each beat is the pumping action of the heart as it moves blood. On average, a person’s heart beats 100,000 times each day. That is over 35 million beats a year and over 2.5 billion beats during an average lifetime. The human heart has to pump 5.6 liter (about six quarts) of blood every 20 seconds. In an average lifetime the heart pumps over 55 million gallons of blood. That is a lot of pumping!

The blood stream is the supply train for the body. Many of the resources necessary for life are carried by the blood to all the cells in the body, including nutrients, oxygen, and water. The body’s cells must carry out many metabolic reactions in order to survive, grow, repair, or replicate. All of these processes require energy, and oxygen is required for cells to obtain energy. Therefore, all cells need a constant supply of oxygenated blood.

Recall the poster of the human body systems you and your classmates made earlier. Think about how closely associated the cardiovascular and the respiratory systems were. The blood cells in the cardiovascular system are oxygenated as they pass through the lungs in the respiratory system.

The heart must move both oxygenated blood from the lungs to the body and un-oxygenated blood from the body back to the lungs. The human heart has many different components that work together to insure the proper movement of blood. The structure of the four-chambered heart is designed so the oxygenated blood does not mix with the un-oxygenated blood. The four-chambered design allows the heart to act like two separate pumps keeping the oxygenated and un-oxygenated blood from mixing. One pump moves blood from the heart to the lungs, and the second pump moves blood from the heart to the body. The action of the two halves or pumps of the heart must be carefully coordinated in order to keep the blood circulating and going in the proper direction. To understand the design of the heart, it is important to examine the structures of the heart and to study the direction of the blood flow through the heart.

In this activity, you will make drawings of the structure of the heart and indicate the direction of the blood flow through the heart. The diagrams you study and draw in this activity will help you to identify the actual structures of the heart when you dissect the four-chambered sheep’s heart in the next activity.

Activity 2.2.2: What Does a Heart Really Look Like?

Introduction

The human heart is a four-chambered structure designed to pump blood in specific directions. The heart is made of various cardiac tissues, each having a specific function. To understand how the heart functions you must first understand the actual physical structure and organization of this amazing organ.

In this activity, you and a partner will dissect a sheep’s heart, a four-chambered structure that is a smaller version of your own heart. You will use the Internet to find information about the heart muscle and the various cardiac tissues in preparation for studying how the heart functions. You will use a microscope to observe professionally prepared slides of cardiac tissues in order to compare and contrast characteristics of the tissues.

Activity 2.3.2: What Makes Your Heart Beat Faster?

Introduction

Since you were young, one of the first things your physician did when you went for an office visit was listen to your heart beat. Heartbeat sounds are a result of blood moving through the various parts of the organ. A physician learns to recognize normal sounds from abnormal ones. The rhythms of the heart beat, as well as the heart rate, are also clues as to the general condition of a person. Changes in these factors can be indicators of potential medical problems. For example, low blood volume might be caused by internal bleeding or dehydration and may cause the heart to beat faster as it tries to maintain blood pressure and adequate blood supply.

Your heart beats at a steady rate. When you are at rest and relaxed, the beat is very constant. However, if you exert yourself by doing physical activity, your heart rate will increase. Many pieces of exercise equipment have heart rate monitors so the person exercising can watch his or her heart rate and increase it just enough to get the benefits of aerobic exercise and not over-stress the heart by getting the rate too high.

Scientific studies have shown that unusual amounts of stress can cause an increase in heart rate. You may have heard stories about people doing amazing things, such as lifting a car off a child or running great distances in a short amount of time. This extraordinary burst of strength is due to the release of large amounts of epinephrine (also known as adrenaline). Epinephrine is the “fight or flight” hormone and its release triggers a number of physiological changes, including an increased heart rate. These involuntary physiological responses are controlled by the nervous system signaling the endocrine system to release molecules that will stimulate the cardiovascular system. When a person is frightened or stressed, his or her body is preparing to fight whatever is frightening him or her, or to run away quickly. That is why epinephrine is referred to as the “fight or flight” hormone. In less extreme examples, you may have felt your heart beat faster when something frightened you or when you physically exerted yourself. This increase in heart rate was also due to epinephrine.

In this activity, you and a partner will use the steps of experimental design to plan and conduct experiments in order to investigate the effect of the “fight or flight” response on heart rate. This response will be stimulated by sudden exposure to cold temperatures. You will also investigate the effect of increased physical activity on heart rate.

Activity 2.3.3: What Is Blood Pressure?

Introduction

Have you ever heard anyone say he or she had high blood pressure or heard someone say what you were doing was causing that person’s blood pressure to rise? Maybe you’ve heard the public service announcements that call high blood pressure the silent killer. So, just what is blood pressure and why is it so important?

You have known since you were a child that water pressure in a hose changes based on several factors. In fact, you probably made changes like squeezing the hose or narrowing the outlet to increase the speed at which the water was released, bending the hose to stop the flow of water completely, or turning the faucet to slow the speed so you could get a drink. All of these are ways to change the water pressure inside the hose. Your cardiovascular system is not that different from these examples.

Blood pressure is caused by the movement of blood through the vessels in your body, the veins and arteries. It measures the force applied to the arterial walls as the heart pumps blood. The pressure is determined by the amount of force and the quantity of blood being pumped. High blood pressure can be detrimental and even dangerous. Many factors can influence changes in blood pressure. In fact, it is continually changing based on activity, diet, temperature, emotional state, body position, medication use and overall health. Another factor that can change blood pressure is the same “fight or flight” reaction controlled by the nervous system you examined in the last activity.

In this activity, you will work with a partner and measure blood pressure, explore factors that might influence it and learn what various blood pressure readings indicate about the health of a person. You will use the experimental design process to create a procedure to investigate a factor that might influence blood pressure and write a formal Laboratory Report.

Activity 2.3.4: The EKG—What Can It Tell Us?

The following is used with permission of Vernier Software and Technology. This activity is based on the experiment “Analyzing the Heart with EKG” from the book Human Physiology with Vernier, written by Diana Gordon and Steven L. Gordon, M.D.

Introduction

Human body systems depend upon electrical impulses to send and receive messages. This electrical energy is what keeps the heart beating. The electrical activity in the heart can be monitored and recorded in the form of a graph. The graph made in this process is called an electrocardiogram and is abbreviated as EKG or as ECG. This has become a very valuable tool used to assess the activity in the heart muscle. Medical professionals are trained to study an EKG and use it to diagnose heart abnormalities such as irregular heart beat, irregular speed of contractions, angina (tissue damage), or even tissue death (myocardial infarction).

An electrocardiogram (ECG or EKG) is a graphical recording of the electrical events occurring within the heart. In a healthy heart there is a natural pacemaker in the right atrium (the sinoatrial node) which initiates an electrical sequence. This impulse then passes down natural conduction pathways between the atria to the atrioventricular node and from there to both ventricles. The natural conduction pathways facilitate orderly spread of the impulse and coordinated contraction of first the atria and then the ventricles. The electrical journey creates unique deflections in the EKG that tell a story about heart function and health (Figure 1). Even more information is obtained by looking at the story from different angles, which is accomplished by placing electrodes in various positions on the chest and extremities. By using different electrode positions, the physician can focus on the electrical impulses of specific regions of the heart to detect abnormalities or damage.

How does the heart generate an electrical current? Before we explore how the heart generates a charge, think about a battery and how it generates an electrical current. The ends of a battery are called poles and one end is positive and the other end is negative. If a wire is used to connect the two poles, then electrons move through the wire from one pole to the other to generate an electrical current. Now let’s consider how the heart

muscles generate an electrical current. At rest, the heart muscle cells are polarized because there are more positively charged ions on the outside of the cell and more negatively charged ions inside (similar to the poles of the battery). When the permeability of a heart cell’s membrane changes, the negatively-charged ions move to the outside of the cell and the positively-charged ions move to the inside of the cell. This flow of electrons produces an electrical current. The flow of electrons begins at one end of the cell and continues to the other end. This initial flow of electrons is called depolarization. It is called depolarization because as the ions move across the membrane there will be a point in time where there are an equal number of negative charges outside the cell as inside, so the cell is no longer polarized; at this point it is depolarized. Conversely, as the negative ions return to the inside of the cell and positive ions return to the outside, the cell is becoming polarized again; therefore this process is called repolarization.

The electrodes of the EKG sensor detect the electrical current produced by the movement of the ions in the heart cells. The electrodes detect the electrical impulse being produced by the heart by detecting the difference between the charges in the areas where the electrodes are attached. The greater the intensity of the impulse, the greater the difference in the charges, and the larger the upward or downward peak will appear on the EKG. A positive voltage reading (upward peak) will occur when the area where the negative terminal is attached is electronegative (more negatively charged) compared to the area where the positive terminal is attached. A negative voltage reading (downward peak) will occur when the reverse situation occurs—the area where the positive terminal is attached is more negatively charged compared to the area where the negative terminal is attached. If there is no charge difference between the two areas where the electrodes are attached, then the EKG reading is zero.

Figure 1:

Five components of a single beat are traditionally recognized and labeled P, Q, R, S, and T. The P wave represents the start of the electrical journey as the impulse spreads from the sinoatrial node downward from the atria through the atrioventricular node and to the ventricles. Ventricular activation is represented by the QRS complex. The T wave results from ventricular repolarization, which is a recovery of the ventricular muscle tissue to its resting state. By looking at several beats, you can also calculate the rate for each component.

Doctors and other trained personnel can look at an EKG tracing and see evidence for disorders of the heart such as abnormal slowing, speeding, irregular rhythms, injury to muscle tissue (angina), and death of muscle tissue (myocardial infarction). The length of an interval indicates whether an impulse is following its normal pathway. A long interval reveals that an impulse has been slowed or has taken a longer route. A short interval reflects an impulse which followed a shorter route. If a complex is absent, the electrical impulse did not rise normally, or was blocked at that part of the heart.

Lack of normal depolarization of the atria can cause the P wave to be absent. An absent QRS complex after a normal P wave indicates the electrical impulse was blocked before it reached the ventricles. Abnormally shaped complexes result from abnormal spread of the impulse through the muscle tissue, such as in myocardial infarction where the impulse cannot follow its normal pathway because of tissue death or injury. Electrical patterns may also be changed by metabolic abnormalities and by various medicines.

In this experiment, you will use the EKG sensor to make a graphical recording of your heart’s electrical activity, and then switch the red and green leads to simulate the change in electrical activity that can occur with a myocardial infarction (heart attack). You will identify the different components of the waveforms and use them to determine your heart rate, and determine the direction of electrical activity for the QRS complex. You will also analyze electrocardiograms that show unusual heart activity and determine what is abnormal about the wave forms.

Activity 3.1.1: What Is in that Stuff We Eat?

Introduction

Anna Garcia, the victim from Unit 1, had a very large amount of glucose in her blood at the time of her death. The high level indicates that she had eaten a large meal not too long before her death and that she was probably diabetic. The presence of medications in her blood that are typically used to treat diabetes confirms the diagnosis. Diabetes is a metabolic disorder caused by the inability of cells to remove glucose from the blood. Glucose is an end product of the digestion of food. In order to understand how glucose gets into the blood in the first place, we have to look at what is in the foods we eat.

Think back to yesterday. What, when and where did you eat? How many times did you eat during the day? When you really think about it, eating is a very important part of almost everyone’s day. Many people schedule their day around their daily eating; consider how often you check the clock to see how close it is to your lunch time, or how you know it is close to dinner time without looking at the clock. Food is an integral part of our culture and has social, economic and, most importantly, physical implications. It has been said, “We are what we eat.” What does that statement mean?

Your body is powered by the energy obtained from food. Your body disassembles the food, bit-by-bit, and captures the energy stored in the molecules that formed the food. This disassembly requires multiple body systems to work together. The digestive system begins the process by mechanically and chemically breaking down the food into its component molecules. These molecules are then absorbed through the small intestine and travel via the circulatory system to all the regions of the body. Finally, the cells in the tissues of the body capture the energy as the food molecules are broken into ever smaller molecules, and this process requires oxygen obtained by the respiratory system.

In this activity, you will determine the definition of various terms commonly used on food labels, and then analyze food labels to determine the nutritional content of the respective food items.

Activity 3.1.2: How Much Energy Is in Food?

Introduction

Why is food considered fuel for our bodies? Consider that one type of fuel for a car is gasoline; the gasoline releases energy as it burns and this energy is used to run the engine. If there is no fuel, there is no energy to run the engine and the car does not work. The same is true with our bodies: without food we would starve to death because our cells would not have enough energy to function. The energy in the food we eat is converted into energy our cells can use, which then allows us to walk, think, see, and talk—just as the energy in gasoline is converted to energy the engine can use to run and move the car.

As you observed in Activity 3.1.1, food labels list the number of calories in a serving of a food; the number of calories is an indication of the amount of energy that a serving of food provides to the body. When referring to food, a calorie is the amount of energy needed to raise the temperature of 1 kg of water 1° C. The number of calories in a piece of food is determined by measuring the increase in temperature of a known volume of water when a portion of the food is burned. This process for measuring the amount of energy in food is called calorimetry.

The word calorie is confusing because there are two definitions of the word and they differ by a factor of 1000. This is similar to confusing a ten dollar bill with a penny. In chemistry, a calorie is the amount of energy needed to raise the temperature of 1 g of water 1° C. The calories listed on a food label are actually kilocalories in chemistry because the amount of water being heated is a kilogram instead of a gram. A kilogram is 1000 times more than a gram.

It was considered cumbersome to use the term kilocalorie when referring to food, so the prefix was dropped. For years when the term calorie was used to refer to food, it was written with a capitol C. A Calorie was the energy to raise the temperature of 1 kg of water, and a calorie was the energy to raise the temperature of 1 g of water. Even that practice has fallen out of favor in recent years and both types of calories are written with lower case letters. Because of the confusion, most scientists have abandoned the term calorie in favor of the Standard International metric unit of measure for energy called the Joule. One calorie (chemistry) is equal to 4.186 joules, and one Calorie (food) is equal to 4186 joules.

As you observed when you analyzed the food labels, different foods contain different amounts of calories. An average person should consume about 2000 calories per day. To measure the number of calories in a piece of food, the food is ignited and the amount of energy in the food is determined by measuring the increase in temperature of water due to the heat given off by the burning food. This process is performed in an apparatus called a calorimeter. In this activity, you will make a simple calorimeter to measure the amount of energy in a variety of food samples.

Activity 3.1.3: What Makes All Matter?

Introduction

Imagine the human body as a gigantic test tube with thousands of chemical reactions taking place at one time! Because the ingredients (or resources) for many of these reactions come from the food you eat, your diet is very important. Most of the chemical reactions involve energy. The body cells ultimately gain energy or use energy depending on the reaction. In this activity, you will apply the basic principles of chemistry you learned in the interactive presentation Introduction to Molecules.

As you learned, all matter, living and non-living is composed of elements, the basic building materials of all substances. Scientists have identified and named 117 elements, 92 which occur naturally. Twenty six elements are normally found in your body. Four of the 26 make up approximately 96% of your total body mass. These four are carbon, oxygen, hydrogen and nitrogen. Eight others make up another 3.8% of body mass. These include potassium, calcium, sodium, chlorine, phosphorous, iron, magnesium and sulfur. Additionally, there are trace elements found in tiny quantities; these include iodine, copper, selenium, aluminum, and fluorine. Scientists do not currently know all of the functions these trace elements have in our cells.

Elements combine in many different ways to create substances that are necessary for the thousands of chemical reactions in your body. To understand body functions, it is important to understand what constitutes a chemical reaction and how reactions occur. In this activity, you will use model kits to gain further understanding of basic chemical principles by building models of some very important molecules used by the human body. Building these models will help you to develop an understanding of how chemical compounds are formed and what happens when they are broken apart in chemical reactions.

Activity 3.1.4: Where Is the Energy?

Introduction

Let’s think about the interactive presentation about molecules you completed earlier. You read and made models of elements, molecules, and compounds; you also read about the interactions between elements and molecules. In this activity, you will explore chemical reactions in greater detail.

Energy is involved in all chemical reactions. In fact, energy is involved in some way with all the events occurring in your body. We need energy to stay alive! So where does all this energy come from? Most of you probably answered from our food. But what does that really mean? When you look at a banana, where is the energy? Understanding basic principles of chemistry helps answer these questions.

Chemical molecules have bonds that hold the atoms within the molecule together. These bonds are energy and, generally speaking, the greater the number of bonds, the greater the amount of energy within a molecule. The metabolic processes in your body are designed to capture the energy found in chemical bonds and convert it to energy the body can use for transporting substances, communicating, and moving muscles.

Activity 3.2.1: What Are Macromolecules?

Introduction

Recall the food labels you examined earlier. What information was listed on each of the labels? List below as many of the specific items included on the labels as you can:

Why does a typical American meal include meat, vegetables, and rice or potatoes? What nutrients are you getting from each of those foods? If you don’t eat meat, what do you eat instead? Does that food have the same nutrients as meat?

The foods we eat contain the nutrients and molecules we need to survive. Some of these molecules are used to build our body parts, some are used to drive chemical reactions necessary for life, and others are used as sources of energy. Many of the molecules in our bodies are very large and are made by combining smaller molecules. These very large molecules are called macromolecules.

Macromolecules are an interesting and diverse group of organic compounds with a variety of functions. Macro means big or large, and a macromolecule is a large molecule. There are four types of organic macromolecules: proteins, carbohydrates, nucleic acids, and lipids (fats).

Some macromolecules are also polymers. A polymer is a large molecule made of many smaller repeating sub-units linked together. The smaller sub-units are called monomers. The prefix mono means one, and the prefix poly means many. Consequently, a monomer is one of something and a polymer is made of many monomers. The pattern or sequence of the repeating sub-units determines the characteristics of a particular polymer. Proteins, carbohydrates, and nucleic acids are all organic polymers.

Lipids are not polymers because they are not composed of a single type of sub-unit. Instead of being constructed of repeating smaller molecules, lipids are aggregates (mixture) of multiple molecules. Lipids are often smaller than the other types of macromolecules. Even though lipids are not polymers and are smaller than the other macromolecules, they are generally considered to be a macromolecule because they can be very large and they are formed by the combination of smaller molecules. Because different lipids are made from different types of molecules, their basic structures are very different. The unifying features of all lipids are that they are primarily composed of hydrogen and carbon atoms and are insoluble in water.

In this activity, you will take a much closer look at the structure of some of the molecules listed on the food labels and begin to develop an understanding of their functions in your body.

Project 3.2.2: Which Molecule Am I?

Introduction

Eating a balanced diet is necessary for good health and it is important to know what nutrients are in the foods we eat. In previous activities you observed that carbohydrates are a great source of energy. Proteins are crucial in our diet for a number of reasons including building tissue, fighting disease, and facilitating chemical reactions. Lipids have equally important functions, including cell membrane and hormone production. To maintain homeostasis, the correct amount of each of these nutrients is needed.

Scientists analyze the chemical components of a substance in a variety of ways; one of the simplest methods is to use chemical indicators. An indicator is a substance that changes to indicate the presence of a particular compound or type of compound. The indicator may change color or temperature, or produce some other substance, such as, bubbles or a distinctive odor. The change in the indicator is due to a chemical reaction between the indicator and the tested substance. Indicators are very specific and work based on the chemical compositions of the indicator and the substance being detected. Some indicators are sensitive to temperature, pH, and other environmental conditions. It is necessary to know the optimal conditions for using each indicator. Generally, the easiest indicators to use are ones that change color to indicate the presence of a substance.

Benedict’s solution is an indicator that can be used to test for monosaccharides (simple sugars). Benedict’s solution is light blue in color. However, when it is heated in the presence of simple sugars, it turns from blue to green or yellow/orange or even to red. The final color depends on the amount and type of monosaccharide. Benedict’s solution needs to be heated to work properly.

Lugol’s Iodine can be used as an indicator for starch. Lugol’s Iodine is yellow or light brown in color; in the presence of starch, it turns dark purple or even black.

Biuret solution is a protein indicator. Biuret solution is a light blue color; in the presence of protein, the color changes to violet or purple. The shade or darkness of the color depends on the type and concentration of the protein, and can range from a very light violet to a deep purple.

Fats and lipids leave a translucent mark on brown paper. Translucent means light can pass through, although distinct images may not be seen through it. Moist foods can be applied directly to brown paper to test for lipids; dry foods can be tested once they are made into an alcohol extract. This is done by grinding the food and placing it in alcohol, and applying samples of the liquid extract to the paper.

In Project 3.2.2 you will use these indicators to determine which common foods contain sugar, starch, protein, and lipid. To begin, you will need to check positive controls for each of the tests. A positive control is a test using a substance known to test positive in the assay. Testing the positive control allows you to see how a positive test should appear, and ensures the reagents and protocols are working properly.

Activity 3.3.1: What Are Action Molecules?

Introduction

Have you ever heard anyone say, “Build strong bones and muscles, eat protein”? As you read earlier, proteins are a very important type of macromolecule found throughout your body. Proteins not only build the body structures, including muscles and bones, they also are involved in

many other functions. Proteins are made from the binding together of amino acids in specific sequences. You could think of the twenty amino acids as letters, and the proteins as long words. Imagine how many words consisting of between 50 and 5000 letters you could make with a twenty letter alphabet! That analogy illustrates the diversity and range in size of proteins. Proteins have a variety of shapes, sizes, chemical compositions, and chemical reactivity. They include thousands of different substances which can be classified into five basic types: structural, regulatory, immunological, transport and catalytic. In this activity, you will focus on the action or catalytic proteins; these proteins, called enzymes, act as catalysts to facilitate chemical reactions.

Chemical reactions are essential for life and occur in all living tissues. Regulating homeostasis depends upon properly maintaining these reactions. Enzymes are an important component for that maintenance. Enzymes are catalysts. A catalyst facilitates or helps a reaction to occur more readily by reducing the energy required for the reaction to occur. The catalyst is not part of the actual reaction, does not change the chemical reaction, and is not permanently altered by reaction. It can be used over and over again to repeatedly facilitate a reaction. Let’s use an analogy to illustrate the action of a catalyst.

Suppose you see a new MP3 player. It is the newest version and has many cutting edge features. Your reaction may be that you want to buy the player. Unfortunately, the player costs more money than you have. In this case the amount of energy (money) to drive the reaction (purchase) is too great for the reaction to occur. Now let’s suppose that a store has a sale on MP3 players, so the price is reduced to a level you can afford. Now the reaction (purchase) can occur. The catalyst in this analogy was the sale. The sale lowered the amount of energy (money) for the reaction to occur. After your purchase, the sale continued and other reactions (purchases) were made by other people.

Most chemical reactions in the body are dependent upon enzymes. Enzymes are highly specific and work on only one substance called its substrate. In this activity, you will learn why enzymes are specific for a particular substrate. You will also investigate if changes in environmental conditions impact how efficiently an enzyme functions. This activity will prepare you for the next project when you will be experimenting with real enzymes.

Activity 3.4.1: Can Negative Feedback Be a Positive Thing?

Introduction

Have you ever considered how the thermostat in your home regulates the temperature automatically, so you don’t have to keep getting up to turn the heat on or off? How often have you had to “tell” your body to keep your internal body temperature at 98.6 degrees Fahrenheit? The convenience of the first example and the amazing process of the second are the results of something called feedback. Feedback mechanisms have been used in engineering, machines, and the development of new technologies since humans started investigating the use of tools.

In biomedical sciences, we are interested in feedback loops in the body. Many metabolic processes, in a variety of human body systems, are controlled by biofeedback mechanisms. The control of body temperature, heart rate, and the concentration of sugar in the blood are all controlled by feedback mechanisms.

There are actually two types of feedback mechanisms: negative feedback and positive feedback. In this instance, the terms positive and negative do not infer good or bad. Instead, the terms refer to the effect the input of information (feedback) has on the output (action) of the system. Positive feedback causes a reinforcement of the original action so the input causes the reaction to increase. Negative feedback causes the system to stop doing the original action and to either take no action or to do an opposite action.

The furnace in your home works by negative feedback. As the temperature goes down in your house, the thermostat sends a signal to turn on the furnace so the temperature will go back up. When the temperature gets up to a specific point, the thermostat gives the furnace the signal to stop. The action of the thermostat induced the furnace to do the opposite of what it was doing. When the furnace was off, the signal from the thermostat turned it on; when the furnace was on, the signal from the thermostat turned it off. The effect of the feedback from the thermostat was to change the original action of the furnace system. The overall result is the maintenance of a stable temperature in your home.

Let’s look at an example of positive feedback. Remember, positive feedback causes an increase in the reaction that was already occurring. As the pressure (input) on the gas pedal of a car is increased, the car increases speed. Positive feedback is telling the system to keep doing what it was doing.

In this activity you will investigate three feedback loops in the human body. The first two, the insulin-glucose feedback and the adrenaline-cardiovascular system, are assigned. You will choose the third loop you want to investigate.

Activity 3.4.2: Why Is Too Much Sugar in Blood Bad?

Introduction

Anna Garcia, the woman described in Unit 1, died of a heart attack. However, she had several other medical conditions that probably contributed to her heart attack and affected her life. Remember she had a very high glucose concentration of 425 mg/dL at the time of her death. For a healthy non-diabetic person the glucose concentration will be in the range of 70 to 115 mg/dL; immediately after eating a meal high in sugar or simple carbohydrates, the concentration may increase to 140 to 160 mg/dL. It is never normal to have a glucose concentration as high as Ms. Garcia’s. So what difference did it make that she had such a large amount of glucose in her blood? Why is too much sugar in blood bad?

As you studied in the last unit, blood is the river of life. It transports the nutrients, oxygen, enyzmes, and hormones the body’s cells need to function and survive. Many molecules dissolve in the plasma portion of the blood, including glucose. Imagine dissolving a large amount of sugar in water. What would be the characteristics of that solution? Now imagine that solution flowing through someone’s arteries and veins.

In this activity, you will use a model of a cell and the blood stream to observe the effects of a high glucose concentration on a cell. Remember cells are surrounded by a semi-permeable membrane that regulates which molecules and substances go in and out of the cell. It is referred to as semi-permeable because of its selective nature. If nothing could go in or out, it would be impermeable; if anything could go in or out, it would be permeable. Instead, the cell membrane uses a variety of transport mechanisms to allow some substances in and to prevent others from entering; hence it is referred to as semi-permeable.

You will use a semi-permeable membrane, called dialysis membrane, as a model of the cell membrane. Inside the membrane (the cell) you will add a solution that is isotonic (similar ionic concentration) to the normal fluid found inside cells. You will expose this model cell to different concentrations of sugar to see the effect on a cell if the surrounding fluids, including blood, have a high glucose concentration.

Project 3.4.3: How Does Insulin Work?

Introduction

How would your life be affected if you no longer had convenient methods of communication? Imagine if you had no phone, no instant messaging, no computer, and no pen or paper. Communication is something we often take for granted and yet it impacts many areas of our lives. In fact, not only does communication affect our interactions with other people, it is vitally important to the cells inside our bodies.

The communication that exists in cells is an amazing process that depends on molecules that travel from one cell to the other. This chemical communication is highly specific and often involves protein molecules. The specific protein will be released by one cell and travel to a second cell. The protein binds to the second cell because that cell has a receptor for it. When the protein binds to the receptor, a cascade of events in the second cell are initiated. The specific protein molecules are referred to as signal molecules because they carry the signal from one cell to another. Signal molecules are also called ligands because they bind to other molecules, causing a reaction of some sort. The signal protein or ligand binds to a specific receptor on the surface of the cell. The location where the ligand attaches to the receptor is called the receptor site.

Once a signal molecule binds to a receptor, multiple events occur within the cell to transfer the message to other parts of the cell and to induce the cell to act on the message.

Earlier in this unit you learned about the lock and key model to explain the specificity of the reaction between an enzyme and its substrate. The signal molecule and receptor work in the same way. They must fit together. If both molecules are not the correct shape, they will not fit or bind together, and the signal is not received.

You may have guessed by now that insulin and glucose are related to signal proteins, receptors, and receptor sites. In this project you will investigate how insulin and glucose are connected to cell communication.

Imagine that you are a healthcare professional who has the task of explaining the connection between insulin and glucose to a group of adults who are at risk for diabetes. Your task is to explain why insulin is necessary for glucose to enter the cells.

In this project, you will use the design process to create a 3-D working model demonstrating how insulin is needed to move glucose into cells. You will take the role of the health care professional and present the model to your class, the adult audience.

Activity 3.4.4: What Is Diabetes?

Introduction

A contributing factor in Anna Garcia’s death was diabetes. She was not alone in having this disorder. According to the National Institute of Health (NIH), diabetes is one of the top three health issues facing Americans in the 21st century. NIH scientists estimate 20.6 million Americans currently have diabetes and another 41 million are thought to be pre-diabetic and at serious risk for getting the disorder in the near future. Scientists at the Center for Disease Control (CDC), in Atlanta, have said one way to evaluate the seriousness of the epidemic is to look at diabetes statistics in a 24-hour period. Currently in the United States, 4,100 new cases are diagnosed every day. Every 24 hours complications from diabetes lead to: 230 amputations, 120 new diagnoses of serious kidney disease, and 55 people lose their vision. In the United States, billions of dollars are spent each year on health care costs related to the treatment of diabetes.

You have learned that insulin and glucose have a very important partnership. Glucose is needed for cellular energy and glucose cannot enter the cell without the help of insulin. The relationship between insulin and glucose is essential for maintaining all metabolic processes because cells need energy to do the metabolic processes. When insulin is no longer produced, or when cells no longer respond to it, diabetes occurs. Diabetes is one of the most serious health issues facing the United States and other developed countries today. Although it is not always possible to prevent diabetes, effective treatments are available that limit the serious side effects. In some cases, life style choices can prevent diabetes.

In this activity, you will learn more about one of the two types of diabetes. You will work in a team and produce either a poster or a brochure that is appropriate to display or distribute in a physician’s office for the purpose of educating patients about diabetes. You will share your finished work with a team that researched the other type of diabetes. In the end, all students are expected to be able to discuss the causes, symptoms, effects, and treatments for both Type I and Type 2 diabetes.

Activity 4.1.1: What Are Sickle Cells?

Introduction

The entries you read in “The Sickle Cell Diaries” provided a firsthand account of life with the disease. So just what is the cause of the pain and the fatigue the author described?

The disease is named “Sickle Cell” because of the unusual shape of red blood cells in people with the disease. The red blood cell is a specialized cell which has the primary purpose of carrying oxygen to the body’s cells. Hemoglobin, a protein, fills the interior of the red blood cell and oxygen molecules bind to it. The body’s cells use the oxygen to complete the series of chemical reactions that release energy from food. The red blood cell is well designed for its purpose. In this activity, you will observe the structure of normal and sickle red blood cells and record your observations in your laboratory journal.

As a result of this activity, you will be able to answer the following questions: How are the shapes of sickle and normal red blood cells different? What problems could the shape of sickle red blood cause in the circulatory system?

Activity 4.1.2: Clinical Symptoms and Complications of Sickle Cell Disease

Introduction

As you observed in the last activity, sickle red blood cells have a markedly different shape than normal red blood cells. The sickle cells contain a different hemoglobin molecule than the normal cells. Remember that the role of the red blood cell is to carry oxygen from the lungs to all the cells in

the body. The hemoglobin found in sickle cells does not bind oxygen as well as the normal molecule. Also, the sickle cell hemoglobin tends to stick together and form long chains. The deformed shape of the sickle cell is due to the long chains of hemoglobin molecules. In this activity, you will research what happens to people with sickle cell disease.

As a result of this activity, you will be able to answer the following questions: What effect does the altered shape of the red blood cell have on the health of the individual? What are the physical symptoms of sickle cell disease? When a person has sickle cell disease, what health complications can occur? What is the treatment for sickle cell disease? What is the prognosis for a person with sickle cell disease? What is the difference between someone having the sickle cell trait and having sickle cell anemia?

Activity 4.1.3: World Distribution of Sickle Cell Disease

Introduction

In Activities 4.1.1 and 4.1.2, you observed that sickle cell disease causes red blood cells to become deformed and that this disease causes several health complications including anemia, organ failure, increased susceptibility to infections, and pre-mature death. Diagnosis of sickle cell disease is made by doing blood tests to examine the hemoglobin.

When a disease with serious health complications is discovered, doctors and the public want to know more about it. The first question asked is “Who has the disease?” The next questions are “How is the disease spread?” and “Who is at risk of getting it?” The next activities will allow you to provide answers to these questions about sickle cell disease.

Epidemiologists are scientists who study the spread of disease in order to determine where and when the outbreak began in the hopes of determining its cause. The goal is to use that information to stop the spread of the disease by preventing people from becoming infected.

In this activity, you will investigate where in the world sickle cell disease occurs in order to determine who may contract the disease.

Activity 4.2.1: What Are Chromosomes?

Introduction

How many times have you heard that you look just like your father, mother, uncle, grandparent, or cousin? Have you ever wondered why people in the same family have similar traits? What do we get from our parents that dictate how we look?

In Activity 4.1.3, you observed that sickle cell disease is very common in some parts of the world and occurs very rarely in other areas. The highest incidence of the disease is in selected countries of Africa including Nigeria, Angola, and the Democratic Republic of Congo.

Unlike the flu or colds which are caused by viruses and are contagious, sickle cell disease is passed from parents to children. It is a disease that is inherited before birth. It is not contagious, so being near someone with the disease does not increase the risk of getting the disease.

There are several human diseases that are inherited from parents including Tay Sachs, hemophilia, cystic fibrosis, Huntington’s disease, polycystic kidney disease, hemachromatosis, and sickle cell disease. These diseases do not involve bacteria or viruses; instead they are caused by changes in the chromosomes.

Each of us receives one copy of each of the 23 chromosomes from each of our parents. Therefore, our cells contain 23 pairs of chromosomes, for a total of 46 chromosomes. Remember, fertilization is the fusion of the nucleus from the sperm with the nucleus of the egg. A key difference between a fertilized and non-fertilized egg is that the fertilized egg contains chromosomes from two individuals, father and mother.

To keep things straight, different human chromosomes were given identification numbers ranging from 1 to 22. One pair of chromosomes is not included in the numbering system because these chromosomes determine whether the baby will be male or female. This pair is referred to as the “sex chromosomes.” Instead of numbers, the sex chromosomes are identified as the “X” and the “Y” chromosomes.

Instructions on the chromosomes determine the traits or characteristics of the person. Simple examples of traits include hair, eye, and skin color. More complex examples of traits include personality, height, and weight. In the case of inherited diseases, the presence of the disease is the trait. So just what are chromosomes and what do they look like when viewed under a microscope?

In this activity, you will observe human chromosomes by using a human tumor cell line grown in a laboratory to prepare a chromosome spread. The tumor cells you will be using are HeLa cells, the oldest human cell line. A cell line is created when cells or tissue can grow continuously in a laboratory if the proper environment is provided. The HeLa cell line was created in 1951 by Dr. Gey at Johns Hopkins Hospital in Baltimore, Maryland, using cells from a cancerous tumor growing in Henrietta Lacks, a 31-year old mother of five. Mrs. Lacks died from the aggressive cancer soon after the cells were taken.

Activity 4.2.2: The Story of HeLa Cells

Introduction

The tumor cell line you used for Activity 4.2.1 was the first human cell line successfully grown in a laboratory. The cell line is now over 50 years old. These cells have been growing and reproducing outside a body for over 50 years!

So where did these cells come from? Who did they originally belong to? How did they become the most famous and oldest human cell line?

In this activity you will read the story of Henrietta Lacks, her family, and the doctors who created the cell line without the family’s knowledge.

Activity 4.2.3: The Doctor’s Point of View

Introduction

In Activity 4.2.2, you read the story of Henrietta Lacks and her family’s reaction to learning that cells from her body were being used in laboratories and classrooms throughout the world. How did you feel about their reaction? If this involved your family, how do you think your family would react?

There are always at least two sides to each story. In this activity, you will read the story of Dr. Gey, the researcher who grew Mrs. Lacks’ cells in a laboratory for the first time.

Activity 4.2.4: How Does Sickle Cell Disease Pass through Families?

Introduction

Do you know people who look just like their father or their mother? Maybe you know someone in your family who looks just like a picture you’ve seen of your great grandfather as a young man. Have you ever wondered how a child could have blonde hair when both parents have dark brown hair? Or, how a child could have blue eyes and no one remembers anyone else in the family having blue eyes? How do traits pass through families?

Some traits that are passed from parent to child can occur more frequently in a population because the child only needs to inherit one copy of the chromosome associated with the trait. These traits are called dominant. The second copy of the chromosome inherited from the other parent also has instructions for a trait, but the trait is not observed and is termed recessive. Usually it does not matter if the chromosome associated with the dominant trait is inherited from the mother or the father. Therefore, only one parent needs to have a copy of the chromosome associated with the dominant trait, and this parent usually also has the trait.

Recessive traits are usually less common in the population because two copies of the chromosome with instructions for that trait must be present for the trait to show. That means a child must inherit the trait on chromosomes from both parents. In these cases, both parents must have the chromosome associated with the trait. Many times neither parent will show the trait because each only has one copy of the chromosome with instructions for the trait. However, if each parent passes that chromosome with the recessive trait to the child, the child will show the trait. This can lead to surprises for the parents because they do not show the trait and may not know that they have the chromosome associated with it.

This is why two parents each with brown eyes, a dominant trait, can have a child with blue eyes, a recessive trait. Each parent had one copy of the chromosome with instructions for brown eyes and one copy of the chromosome with instructions for blue eyes. The brown-eyed trait is dominant, so each parent had brown eyes. They each passed to the child the copy of the chromosome with instructions for blue eyes, so the child had two copies of the instructions for that trait. Therefore, the only instructions the child had for eye color were for the recessive trait of blue eyes.

In Activity 4.1.2, you learned that people with sickle cell disease make abnormal hemoglobin protein which deforms red blood cells. The protein hemoglobin is composed of four subunits, two alpha-globins and two beta-globins. The difference between sickle cell and normal hemoglobin is that the beta-globin subunits used to make the two types of hemoglobin are different. Instructions for making the beta-globin protein are found on Chromosome 11. The region of the chromosome containing the instructions to make a protein or a protein’s subunit is called a gene. Therefore, the sickle cell version of the beta-globin gene located on chromosome 11 is the cause of sickle cell disease. Can a single copy of the gene for the sickle cell version of the beta-globin cause the disease, or do both copies of the beta-globin gene have to be the sickle cell version in order for the disease to occur?

In this activity, you will examine pedigrees of families to determine if sickle cell disease is passed by the inheritance of a single copy of the sickle cell version of the beta-globin gene, or if two copies of the sickle cell gene are necessary for the disease to occur. If a single copy of the sickle cell version of the gene is responsible, then the disease trait is dominant. If two copies of that gene are necessary for the disease to occur, then the disease trait is recessive.

Activity 4.2.6: What Is the Probability?

Introduction

In Activity 4.2.2, you observed that the sickle cell trait is passed from parent to child, and that in order for a child to have sickle cell disease both of the child’s copies of chromosome 11 must have the mutation for sickle cell hemoglobin. In a family with a history of sickle cell trait, they may want to know whether or not future children will have the trait. If the pattern of how the trait is inherited and the individual’s family pedigree are known, doctors and genetic counselors can calculate the probability that an individual will express a trait. Because each parent has two copies (one pair) of every chromosome, there is a 50% chance of either chromosome being passed to a child (just as a coin has two sides and there is a 50% chance it will be heads and a 50% chance it will be tails when it lands after being tossed in the air).

If both copies of a parent’s chromosomes are identical for a trait, then the child can only receive a chromosome with that particular trait. That means the child has a 100% chance of getting that trait, whether normal or disease, from that parent. That is because that is the only version of that trait the parent has to pass to the offspring.

On the other hand, if the parent has two different versions of the trait, a different version on each of the chromosomes in the pair, then there is a 50% probability that one version will be passed to the child, and a 50% chance that the other version will be passed.

The child will receive one copy of each chromosome from each parent. The selection and passing of one chromosome from the father is independent of the selection and passing of the mother’s chromosome. The probability that a child will receive a particular trait is calculated by multiplying the chance of the father passing the trait with the chance of the mother passing the trait. The two values are multiplied because the two events are independent of each other (just as when two coins are tossed into the air; whether one coin lands as heads or tails has no effect on how the second coin will land. It can still land as either heads or tails.).

Refer to Pedigree 1 in Activity 4.2.2. Look at individual I-1. If this person has the normal hemoglobin trait on both copies of chromosome 11, then the only hemoglobin trait he can pass to his child is normal, making it a 100% chance the child will receive a normal hemoglobin trait from him. Now look at individual I-2. If this person has the sickle cell trait on both copies of chromosome 11, then the only hemoglobin trait she can pass to her child is sickle cell. The child has a 100% chance of receiving the sickle cell trait from her. So all of their children (generation II) have one copy of chromosome 11 that is associated with normal hemoglobin and one copy of chromosome 11 that is associated with the sickle cell hemoglobin. Each of these children then has a 50% chance of passing on either the normal or the sickle cell hemoglobin trait to their children. If one of these children has a child with another person who also has a 50% chance of passing on the sickle cell hemoglobin trait, then there is a 25% chance that child will have sickle cell disease. Here is how it is calculated: the 50% or 0.5 chance of one parent passing the trait is multiplied by the 50% or 0.5 chance of the other parent passing the trait (0.5 x 0.5 = 0.25 = 25%).

In this activity, you will examine pedigrees and calculate the probability that an individual has or will receive the mutated chromosome that causes the abnormal hemoglobin associated with the sickle cell trait and disease.

Activity 4.3.1: How Do Chromosomes Carry Information?

Introduction

In the Inherited Diseases PowerPoint, you observed human sperm and egg cells. Remember that the fertilized human egg forms when the nuclei of the sperm and the egg combine to form one new nucleus. The new nucleus contains 46 chromosomes, 23 from each parent. The fertilized egg cell will replicate the 46 chromosomes and divide to form two identical cells each with 46 chromosomes. Then the two identical cells will each replicate their 46 chromosomes and each will divide to form two more identical cells each with 46 chromosomes. Now there are four identical cells. Each of the four cells will replicate their 46 chromosomes and each will divide to form two more identical cells. Now there are eight identical cells. These eight cells will replicate to form sixteen cells; the sixteen will replicate to make thirty-two, and so on. This process continues and approximately nine months after the egg is fertilized a human baby is ready to be born!

Every cell in that baby has copies of the same 46 chromosomes as the fertilized egg—the same chromosomes carried in the father’s sperm and the mother’s egg. All the information cells need to function and all the observable traits of the baby including gender, hair and skin color, facial features, and even the number of fingers and toes are determined by the chromosomes. So how do chromosomes carry all that information?

In Activity 4.2.4, you read that a gene on chromosome 11 contains the instructions for making the beta-globin subunit of hemoglobin. People with sickle cell disease inherited two copies of the sickle cell version of that gene. In this activity, you will view animations of chromosomes in order to visualize the structure of chromosomes, explore the features of chromosome 11 including the beta-globin gene, and investigate genes located on other chromosomes.

Activity 4.3.2: What Is the Structure of DNA?

Introduction

How many times have you heard about DNA? It is the molecule that determines many of your physical characteristics. It is also the molecule that makes you unique. Unless you have an identical twin, no one else has the exact same DNA as you.

In Activity 4.2.1, you made chromosome spreads and used a microscope to observe human chromosomes. Then in Activity 4.3.1, you explored computer animations showing how the chromosome is made of deoxyribonucleic acid (DNA) wrapped around protein molecules called histones. The histone proteins act like a spool to keep the long thread of DNA organized and protected from damage. It is the DNA portion of the chromosome that carries all the information used by the cells.

In this activity, you will explore the structure of DNA by building a three-dimensional model of the molecule and using interactive computer animations.

Activity 4.3.3: How Is DNA Isolated from Cells?

Introduction

You have looked at chromosomes and built a model of the DNA molecule, but just how do scientists get DNA out of cells in order to study it?

Imagine a bowl of vegetable beef soup that contains chunks of beef, potatoes, celery, tomatoes, onions, peas, and carrots in a thick broth. Now imagine trying to separate or isolate the carrots from all the other ingredients.

A cell is a complex living unit that contains many proteins, carbohydrates, lipids, and other components within its cytoplasm and organelles. To be able to work with the DNA, researchers must separate the DNA molecules from all of the other chemicals and materials inside the cell. To accomplish that task they take advantage of the unique chemical properties of the DNA. The same way you might use the unique orange color of carrots to separate them from the rest of the soup.

In Activity 4.3.2, you built a model of the DNA molecule and compared your model to all the models built by your classmates. When you compared the models, the only difference between them should have been the sequence or order of the nucleotides. This is also the only difference between DNA molecules isolated from different living organisms. The double helical structure and chemical properties of the DNA found in all living organisms is the same. That is the founding principle for genetic engineering. In genetic engineering, DNA from one organism is transferred to a second organism which is then able to make the same protein that the first organism made. For example, a section of human DNA containing the gene for the insulin protein was inserted into bacteria, and those bacteria produced the human insulin protein. In fact, the insulin used by most insulin-dependent diabetics is produced by bacteria.

Before genetic engineering can occur, the DNA must first be isolated. In this activity, you will isolate DNA from plant and animal cells. It is very important that you follow the procedure very carefully. Otherwise, your DNA samples will be contaminated with proteins and other cell components. Remember to follow all the safety instructions provided by your teacher.

Activity 4.4.1: What Is the DNA Code?

Introduction

As you observed in the Inherited Diseases PowerPoint, the only material brought by the sperm to the egg was the nucleus containing 23 paternal chromosomes. The fusion of the nuclei from the egg and the sperm created the fertilized egg which then develops into the human embryo. The chromosomes contained the instructions to form the embryo. In Activity 4.3.1, you read that chromosomes contain numerous genes and consist of DNA and proteins. Therefore, the chromosomal instructions must be in the DNA, the proteins, or some combination of the two components.

It took over fifty years from the time DNA was discovered, until it was proven to be the material responsible for passing traits from one generation to the next. As you observed in Activity 4.3.2, DNA is made of four different nucleotides. Considering that proteins are made from twenty different

amino acids, it was hard to accept that a molecule made from only four subunits was capable of carrying all the instructions necessary to pass traits to the next generation. Imagine a written language with words created from only four letters. Would it seem to be as complex as a language with words made from twenty letters?

We now know that the complexity of DNA is not in the number of subunits, but in the arrangement or sequence of those subunits. Just as English words are created by the specific arrangement of letters, the instructions in the DNA are determined by the sequence of the nucleotides.

To learn the causes or pre-dispositions of human disease, many scientists and medical researchers are examining the DNA sequences obtained by The Human Genome Project. The Project was completed in 2003, and was a collaboration of many scientists around the world to sequence the entire human genome. It took 13 years to completely sequence the human genome. A genome is all of the genetic or hereditary information contained in the DNA of an organism.

In this activity, you will examine a DNA sequence in order to determine how the DNA code is translated into a sequence of amino acids which then form a protein.

Activity 4.4.2: What Determines the Shape of a Protein?

Introduction

In Activity 4.4.1, you observed how the sequence of nucleotides in a DNA molecule determines the sequence of amino acids in a protein. As you’ve seen, each different gene carries the code for a different protein. You have studied several proteins in this class including insulin, and hemoglobin. Each of these proteins has a specific purpose in the body, and each has a unique shape. What is it that makes proteins different from each other? What determines the shape of a protein?

To see the different shapes of the molecules you have studied in this class, visit the websites listed below. Insulin: http://www3.interscience.wiley.com:8100/legacy/college/boyer/0471661791/structure/jmol_intro/jmol.htm Hemoglobin: http://www.rpc.msoe.edu/cbm/jmol/1a3n.php.

Remember, it is the DNA code that contains the instructions on how to form the protein. You could think of the DNA code as a language that uses only four letters. English words are created by combining different letters in specific combinations, and these words convey a specific meaning to the reader. For example, consider the word cat. It is created by combining the letters “c,” “a,” and “t” in one specific order. If the same letters are re-arranged, a new word act can be created. The only difference between the two words cat and act is the sequence of the letters, yet the words have very different meanings. The same is true of DNA: the letters are the nucleotides and each word is three letters in length; the “words” or codons then determine the “meaning” or sequence of the amino acids. Different genes use different “words” so they convey different meanings, or code for different proteins.

Because all DNA is chemically the same, the only difference between genes is the sequence of the nucleotides. The sequence of nucleotides then determines the selection and order of the amino acids in the protein. That means proteins must differ in the selection and sequence of their amino acids, and this difference is what gives each protein its shape and ability to function. How does the sequence of amino acids determine the three-dimensional shape of a protein?

In this activity, you will use computer simulations to examine how amino acids interact with each other and their surrounding environment. Note: Portions of this activity are adapted from Unit V Activity 2: How Proteins Get Their Shape: Responding to Water or Lipids, published by the Concord Consortium that is available at http://www.concord.org/~btinker/workbench_web/unitV/act2_wkst_s.html.

Project 4.4.4: How Are Designer Proteins Made?

Introduction

In this unit, you observed how the DNA sequence determines the amino acid sequence and how the amino acid sequence determines the protein’s 3-dimensional shape. Using information about how DNA codes for specific amino acids and how those amino acids interact with each other and the environment, it is possible to engineer a protein with specific characteristics. Many pharmaceutical companies are engineering proteins that can treat or cure diseases. For example, a designer protein was constructed to aid patients with multiple sclerosis, a crippling neurological disorder. The engineered protein is an improved version of a protein normally found in the body called beta-interferon. The protein was engineered by scientists working at the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB, in Hanover, Germany. You can read about this protein at by clicking on this link: Designer Interferon.

In this project, you will design a protein with a specific function. In order to complete the challenge, you will need to apply all the concepts you have learned about DNA structure, DNA coding, and amino acid interactions.

Activity 4.5.1: What Is Karyotyping?

Introduction

In the previous activities, you explored various genetic diseases and the role of chromosomes in the inheritance of traits. In Activity 4.2.1, you used the microscope to observe human chromosomes from the HeLa cell line. Sometimes mistakes occur with the chromosomes. These mistakes include having three copies or only a single copy of a chromosome instead of the normal two copies, losing large sections of a chromosome, or having the translocation of a section of one chromosome to another chromosome. The consequences of chromosomal mistakes can be devastating, and are usually fatal for the fetus. There are a few instances where the mistake is not fatal, but the fetus will develop into an adult with a variety of abnormalities.

One example of a non-fatal chromosomal mistake is Down’s syndrome. Do you know someone with Down’s syndrome? Do you know the cause of the syndrome? Why are the consequences of chromosomal alterations referred to as “syndromes” and not diseases? If you were having a baby, would you want to know if there were any problems with the chromosomes of the fetus?

Because the consequences of chromosomal mistakes are so severe, many women undergo pre-natal testing to check the chromosomes of the fetus. To do this testing, fetal cells are collected and then chromosome spreads are created. The chromosomes are then stained and arranged into karyotypes. In a karyotype, the maternal and paternal versions of each chromosome are paired, and the pairs of chromosomes are arranged by

size from the largest to the smallest. The two sex chromosomes, X and Y, are always placed last. The identification number for each chromosome corresponds to its size, with chromosome number 1 being the largest and chromosome number 22 being the smallest.

Until a few years ago, the chromosomes were always stained with a general dye called Giemsa that created bands of dark color at certain regions of the chromosome. More recently, colored dyes that target specific regions of specific chromosomes have been developed. The dyes are bound to sequences of DNA that target specific chromosomes, so each of the 23 different pairs of chromosomes is stained a different color.

In this activity, you will complete at least three karyotypes, diagnose the condition of the child, and research the effects of the chromosomal mistake on the physical condition of the child.

Activity 4.5.2: Does Changing Just One Nucleotide Make a Big Difference?

Introduction

In Activity 4.5.1, you looked at the effects of major changes in the chromosomes of a person. These chromosomal changes caused multiple physical changes in the individual. Remember, most of the time when there are major chromosomal mistakes, the fetus does not survive. Analysis of karyotypes, as you did in the previous activity, can detect these major changes. Sometimes, however, the change in a chromosome is so small the karyotype appears normal. These changes may involve only a small section of the DNA, even as small as a single nucleotide. Many inherited genetic diseases are caused by these small changes.

In Activity 4.4.1, you observed how the sequence of nucleotides in a DNA molecule determines the sequence of amino acids in a protein. If the nucleotide sequence is changed, then the amino acid sequence may also change.

Any change in a chromosome or the DNA is called a mutation. Sickle cell disease is caused by the mutation of a single nucleotide in the DNA sequence. The change in just one of the over 400 nucleotides that code for -globin is enough to cause all the problems associated with sickle cell disease. Imagine if getting only one answer incorrect out of 400 questions on an exam caused you to receive a failing score on the exam! That is how important some DNA nucleotides are to the final structure and function of a protein.

The sickle form of -globin is created when an adenine nucleotide is changed to a thymine. This changes the code for the sixth amino acid in the -globin protein from GAG to GTG, which causes the sixth amino acid in the protein to become valine instead of glutamic acid.

Hemoglobin has four subunits; it is made by combining two -globin proteins with two -globin proteins ( is the Greek symbol for beta and is the symbol for alpha). That single amino acid replacement in the -globin protein alters the shape and the chemistry of the hemoglobin molecule causing it to polymerize and distort the red blood cell into the sickle shape.

Think back to how you used the sequence or map of amino acids to fold the model of -globin in Activity 4.4.3. Sometimes the sequence of amino acids formed an alpha helix and other times the protein made sharp turns. The selection and sequence of the amino acids are the most important factors determining the shape of a protein. That is why the sequence of amino acids is considered the primary level of protein structure. Primary, in this case, means the first and the most important. If changes are made in the primary structure, then the entire shape and chemistry of the protein may change. The cumulative effect of changing the sequence or selection of amino acids in a protein can be analogous to a snow ball causing an avalanche. One seemingly small change in the sequence of amino acids can result in a devastating disease or health condition due to the altered protein.

In this activity, you will build and examine models of glutamic acid and valine, use computer simulations to visualize the changes in the -globin protein due to the mutation associated with sickle cell disease, and research other diseases caused by changes in a single amino acid.

Activity 5.1.1: Aren’t All Fats the Same?

Introduction

How many times have you heard commercials for “low fat” or “no cholesterol” foods? Why are there so many medications to help lower the amount of cholesterol in people’s blood? Why do food labels list the amounts of saturated, unsaturated, and trans fats in addition to the amount of cholesterol?

In Unit 3 you built a model of a lipid. That lipid, or fat molecule, was a tri-glyceride. It consisted of three fatty acid molecules attached to the glycerol molecule. Remember glycerol is a three-carbon molecule with a long fatty acid molecule attached to each of the carbons. Think back to the reading you did in Unit 3; recall that lipids have many functions in the body including storing energy, transferring cellular messages, transporting materials, forming cell membranes, and protecting organs. There are different types of lipids to perform each of these different functions.

Lipids are a necessary component in your diet. However, it is important that your diet includes the right lipids in the correct amounts. In this activity, you will examine the structures of different types of lipids by building models.

Activity 5.1.2: What Are LDL and HDL?

Introduction

In the last activity, you read that cholesterol is needed for the proper functioning of cells and for maintaining a healthy body. Cholesterol is used to form cell membranes, aid digestion, and insulate nerve cells; it is a precursor to several steroid hormones including testosterone and estrogen.

However, too much cholesterol can lead to health problems, in particular heart disease and blocked arteries which can lead to strokes and heart attacks. Do you know anyone with high cholesterol? Does someone in your family eat a diet low in cholesterol? Have you wondered why there are so many commercials on television for drugs that lower cholesterol? What is the basis for classifying cholesterol as good or bad?

Cholesterol is produced in the liver and absorbed from food as it passes through the intestines. Regardless of where cholesterol originates, it must be transported to all the cells in the body. As with most substances transported through the body, it is carried by the blood stream.

Think back to Unit 3. How do fat molecules and water molecules interact with each other? Cholesterol is a fat and the blood is mostly water. How can the hydrophilic blood carry the hydrophobic cholesterol?

In order to be transported in the blood, the cholesterol molecules are surrounded by hydrophilic proteins. It is the hydrophilic protein that is in contact with the hydrophilic blood, and the hydrophobic cholesterol is sequestered in the middle. Think about a chocolate peanut butter cup: there is peanut butter in the center that is surrounded by the chocolate. Analogously, the cholesterol molecules are in the center and are surrounded by a protein. This complex combination of lipid and protein is called a lipoprotein.

Cholesterol is needed by all cells in the body and one type of lipoprotein, LDL, is responsible for transporting cholesterol to the cells. Another type of lipoprotein, HDL, is responsible for removing excess cholesterol from the blood stream and transporting it to the liver.

Many people have misconceptions about cholesterol, LDL, and HDL. Because of all the pharmaceutical and food marketing, much misinformation has been spread about these molecules. It is not uncommon to hear LDL referred to as the “bad cholesterol molecule” and HDL as the “good molecule.” In reality, both molecules are just doing their jobs in the body, and neither is actually good or bad.

In this activity, you will design and create a brochure or a poster that accurately informs high school and college students about cholesterol, LDL, and HDL.

Activity 5.2.1: How Does PCR Amplify DNA?

Introduction

How many times have you seen a DNA sample collected from a crime scene shown on a television show or movie? Often the sample is taken from a single drop of blood, saliva, or sweat. Then the DNA is compared to a suspect’s DNA that was collected by a simple swab of his or her mouth.

DNA is not floating in the blood, saliva, or sweat. Cells are carried by these fluids and the DNA is inside the nucleus of these cells. The DNA obtained from the blood, saliva, or sweat is isolated from the cells in the drop of fluid. Remember how you isolated DNA from plant cells? Just how do investigators get enough DNA from that drop of blood or mouth swab to be able to analyze it?

Think back to Units 2 and 4 when you examined human blood smears under a microscope. Remember, there were many more red blood cells than there were white blood cells. Mature red blood cells in humans do not contain any DNA. The immature red blood cell destroys its nucleus and the DNA, in order to make room for more hemoglobin molecules. Only the white blood cells in the blood drop contain DNA.

A drop of blood may have as few as 10 cells that contain DNA, and a bead of sweat can have even fewer. In order to get enough DNA from the sample to analyze, the DNA from those few cells is copied over and over again. The laboratory process used to copy the DNA is called the polymerase chain reaction or PCR. Just as a copy machine is used to make multiple copies of a page from a book, the process of PCR makes multiple copies of selected sections of DNA.

When DNA molecules are copied over and over again, the quantity of DNA is amplified. Just as an amplifier on a stereo system increases the sound level, PCR amplifies or increases the amount of DNA.

The polymerase chain reaction is named after the enzyme, polymerase, which copies DNA in cells. It is referred to as a chain reaction because multiple events occur in succession, and these events occur over and over again in the same sequential order. Each time the series of events is completed, one cycle has been completed. If the events repeat ten times, then the process has completed 10 cycles.

In this activity, you will calculate how many copies of a section of DNA can be obtained from a single DNA molecule after 30 cycles of the PCR and will watch animations of how PCR amplifies DNA.

Activity 5.2.2: What Is Familial Hypercholesterolemia and How Is It Diagnosed?

Introduction

Imagine someone dying of heart disease before the age of 20. What could have caused the onset of heart disease so early in that person’s life?

Earlier in this unit, you read about the functions of cholesterol in the body and the roles of the lipoproteins LDL and HDL in transporting cholesterol in the blood. Remember that LDL transports cholesterol to the cells. What would happen if LDL could not bind efficiently to cells, so the cholesterol molecules stayed in the blood and did not enter the cells?

In some families, the risk of heart disease and an early death are very high because a genetic defect leads to very elevated levels of LDL in their blood. The genetic defect causes the LDL receptor on cells to be deformed and inefficient at binding LDL. The result of the inefficient uptake or binding of LDL by the receptor is elevated LDL in the bloodstream, which then leads to the accumulation of a fatty substance called plaque in the blood vessels. The plaque accumulation in the arteries can cause blockages in the blood flow which result in heart attacks or strokes.

One in every 500 Caucasians in the United States has the disorder called familial hypercholesterolemia which is caused by a mutation to the LDL receptor. Many different DNA mutations can lead to defects in the LDL receptor. In many cases, the defect is due to a single mutation in the receptor gene. Often this mutation is referred to as the FH mutation, because it is the mutation that is most closely associated with familial hypercholesterolemia.

To detect the FH mutation, DNA is obtained from the patient’s blood or saliva; the section of DNA containing the LDL receptor gene is then amplified by PCR. The amplified DNA is analyzed to see if there is a mutation. To analyze the DNA, investigators use enzymes to cut the DNA in specific places.

These enzymes are called restriction endonucleases. Where they act is restricted and they cut nucleic acids (DNA). By examining the sizes of the DNA fragments obtained after exposing the DNA to the restriction endonucleases, it is possible to detect mutations or changes in the DNA. This detection is possible because of Restriction Fragment Length Polymorphorism or RFLP. RFLP simply means that when different DNA samples are exposed to the same restriction enzyme the DNA fragments produced by enzyme may be different lengths. The different lengths are due to differences in the DNA sequences of the two samples; the DNA sequence differences are a polymorphism. A mutation or change in the DNA sequence can change where the enzyme cuts the DNA, so the DNA fragments are different sizes than in the normal DNA.

To visualize the DNA fragments and sort them according to size, a process called DNA electrophoresis is used. The DNA samples are loaded into a gel and exposed to electrical currents. The fragments run or move through the gel at different rates of speed. The smaller the DNA fragment, the faster it moves through the gel. The DNA fragments are then stained with a dye and can be observed as lines or bands in the gel.

In this activity, you will use DNA electrophoresis to separate and analyze DNA fragments in order to determine if patients have familial hypercholesterolemia.

Activity 6.1.1: What Are Bacteria?

Introduction

How many times have you heard the following phrases? “Wash your hands before you eat.” or “Don’t touch that! It’s covered with germs.”

What are germs? What do they look like? Are they all bad?

The word germ is commonly used to mean any bacteria or viruses that can make a person sick. In scientific terms, a germ is any cell that can grow to become a new organism. That is why a plant seed that is just starting to sprout is said to be germinating; it is becoming a new plant.

Bacteria are germs because they can easily reproduce. A bacterial cell does not need to mate with another bacterium in order to reproduce. One bacterial cell is capable of dividing itself into two new bacterial cells by a process called binary fission. The term binary means two and fission means to split, and bacteria reproduce by literally splitting in two.

Bacteria are living organisms and need to have an energy source. Some bacteria are capable of converting sunlight or chemicals into energy; others must convert food to energy just like humans. One way to distinguish one type of bacteria from another is by determining what materials it uses for food. For example, some bacteria can digest oil and use it for food, others eat selected types of sugars or fats, and some bacteria are even capable of eating flesh or meat.

Bacteria can damage human tissue in three ways. One way is for the bacteria to directly attack and digest human cells. A second way is for the bacteria to produce toxins or other proteins that travel in the blood stream and damage cells that are not near the site of the actual bacterial infection. The third way is for the bacterial cells to trigger a response by the immune system; as a result, the immune cells or their products damage surrounding body cells during the ensuing battle to kill the bacteria. Some types of bacteria are capable of using all three mechanisms. For example, the streptococcus bacterium that causes strep throat can use all three mechanisms, and this is why it is so dangerous. The bacterium that causes tetanus, Clostridium tetani, releases a toxin that interferes with nerve cells and causes paralysis.

Bacteria are very small, much smaller than a human cell. Single cells can only be observed using a microscope and magnifying them at least 1000x. Bacteria are divided into two main groups depending on how they react to a specific set of dyes called the Gram stain. A microbiologist named Hans Christian Gram developed the staining protocol in the 1880’s, and it remains the first step in classifying or identifying bacteria. If the bacteria appear purple after being treated with the stain, they are classified as Gram positive. The bacteria are considered to be Gram negative if they appear pink. The medications a physician uses to treat a bacterial infection will sometimes depend on whether the bacteria are Gram positive or negative. For example, penicillin is very effective against Gram positive bacteria, but not against Gram negative bacteria.

Activity 6.1.2: How Do Bacteria in the Mouth Affect the Heart?

Introduction

Think back to the autopsy report on Anna Garcia. Remember she had heart valve damage, possibly due to rheumatic fever. The heart valve damage may have been a contributing factor to her having a heart attack, which caused her death. What is rheumatic fever? What causes it? How is the heart involved?

You can probably guess that rheumatic fever has something to do with bacteria of the mouth, and you’re right. Rheumatic fever is caused by the same bacteria responsible for Strep throat, Streptococcus. That is why when you have a sore throat a swab of your throat is taken and tested to determine if the infection is due to Streptococcus or not. If Streptococcus is detected, antibiotics are often prescribed and you are told to not attend school for a couple days. These actions are taken to prevent the spread of the infection to more people because of the risk of multiple complications, including rheumatic fever. These precautionary measures have significantly reduced the incidence of rheumatic fever in the United States.

Rheumatic fever is one example of a bacterial infection having a direct effect on the heart tissue. Another example of a bacterial infection directly affecting heart tissue is bacterial endocarditis. Also known as infective endocarditis, it is a bacterial infection that damages the inner lining of the heart and sometimes the heart valves.

Other bacterial infections do not attack the heart directly; nevertheless, they have a major role in increasing the risk for a heart attack or stroke. For example, bacteria normally found in the mouth have been associated with the build-up of plaque in arteries that leads to atherosclerosis, which is a risk factor for heart attacks and strokes. Not just dentists are suggesting that people brush and floss their teeth daily, cardiologists also recommend it.

In this activity you will research the relationship between oral bacteria and increased risk of heart attack. You will summarize your research in a concept map and design an educational poster for a dentist’s office that informs patients of the relationship between oral health and heart health.

Activity 6.1.3: Which Antibiotic Is the Best Choice?

Introduction

Do you remember ever taking any antibiotics? Are you allergic to any antibiotics? Have you ever taken an antibiotic for an illness or an infection, and it didn’t work? In this Activity we’ll take a closer look at antibiotics and examine their effect on bacteria.

Alexander Fleming was a young medical researcher in 1928 when he noticed something unusual in the bacterial cultures he was growing. He had grown bacteria in Petri dishes and some of the plates become moldy. Where the mold grew, the bacteria disappeared. He hypothesized that the mold was releasing a substance that was killing the bacteria. To test his hypothesis, he grew pure cultures of the mold in broth, filtered the broth to

remove the mold cells, and tested the broth to see if it killed bacteria. It did. He named the antibacterial substance penicillin after the mold, Penicillium notatum. It took nearly 15 years of research before penicillin could be used to treat bacterial infections in humans. During World War II, the availability of penicillin is credited with saving thousands of lives that would have been lost due to infected wounds.

Today many antibiotics are available to treat infections. Most antibiotics are produced by different species of mold and bacteria. The molds and bacteria release the antibiotics to kill other species of mold or bacteria that compete for food or other resources. Antibiotics have no effect on viruses and will not cure a viral infection.

Some antibiotics have limited effectiveness in treating infections. In some cases the effectiveness is limited by how the antibiotic acts on the bacteria to kill it or to inhibit its growth. Penicillin, bacitracin, and erythromycin are effective primarily against Gram-positive bacteria, while streptomycin is primarily effective against Gram-negative bacteria.

Antibiotics that are effective against both Gram positive and negative bacteria are considered to be broad spectrum drugs. Examples of broad spectrum antibiotics include cephalosporin, neomycin, and tetracycline.

Do you remember taking of the antibiotics listed thus far? Think about why you had those medications.

A limitation to the effectiveness of an antibiotic is the development of antibiotic resistance in bacteria. Bacteria become resistant to an antibiotic when they develop a way to destroy the antibiotic or to block its action. For example, bacteria resistant to penicillin produce and secrete a protein that destroys the penicillin molecule before it can harm the bacteria. Antibiotic resistance is a major medical concern today because many strains of harmful bacteria have become resistant to all the commonly prescribed antibiotics. Many public health officials are very concerned because strains of some bacteria are now resistant to all known antibiotics. That means someone who becomes infected with one of these super-resistant strains has no treatment options; if he or she passes the infection to other people, it could become a health crisis as more people become sick and there is no effective treatment.

When a patient is diagnosed with a bacterial infection, the physician will often prescribe a broad spectrum antibiotic or an antibiotic commonly used for the particular type of infection. If the patient’s health does not improve, then the physician may take a sample of the bacteria from the infection site and test several different antibiotics to find the best one to use. The activity you will be completing is the same one performed daily in hospitals to find the most effective antibiotic to treat an infection. You will test several different antibiotics to determine which one is the most effective at preventing the growth of a strain of bacteria.

Activity 6.2.1: What Are Viruses?

Introduction

How many times have you had a cold or the flu? You never get exactly the same cold a second time; each time it is due to a different virus. On the other hand, the flu is due to a single virus called the influenza virus. This virus changes or mutates very rapidly. So the influenza virus that made someone sick last year will return this year, but it will have changed. If the changes are significant, it will appear to that person’s body like a new virus and that person may get the flu again. Usually, the changes are small; if you get the flu one year, it is usually a few years before the virus changes so much that your body does not recognize it and get rid of it before you get sick.

Viruses cause a number of human diseases including polio, chicken pox, measles, small pox, hepatitis B, and mumps. You may not have heard of these diseases because there are vaccines to protect people from getting sick due to infections with these viruses. Some viruses you may be more familiar with are rabies, herpes, SARS and HIV.

Viruses are often confused with bacteria and lumped into the general category of germs. Viruses are as different from bacteria as a fish is different from a monkey. Viruses are not even cells, which leads many scientists to consider them non-living. Viruses are the ultimate parasite; they attach to, take over, and use cells. The overtaken cell is called a host cell. A virus will get its genetic material into a cell, completely take over all the cell processes, and force the host cell to produce new viruses. Because viruses are non-living, they do not require food and do not make any products without the help of a host cell. Some viruses can even remain dormant in the environment for centuries, just waiting for the right kind of cell to make physical contact with it. That contact allows the virus to attach, insert its genetic material, and take over the cell.

Viruses are much smaller than cells. Until the electron microscope was invented in the 1940’s, it was impossible to see a virus. Viruses have many different shapes. They look similar to geometric Christmas tree ornaments.

The structure of a virus determines which cells it can attach to and invade. For example, the smallpox virus only attaches to human cells; it can not attach to dog, cat, fish, or plant cells. Some viruses attach only to certain species of bacteria. Imagine a bacterial cell getting a viral infection! For the bacteria, a viral infection usually means death.

In this activity, you will choose a virus to research and build a model of it. You will show your model to the class and present a report about the virus and its structure. The model can be made from the materials provided or, with your teacher’s permission, you may use other materials.

Project 6.3.1: How Do We Tell Others?

Introduction

Between 1918 and 1920, over 25 million people died from a severe flu infection. More people died from the flu than died during World War I. It is estimated that between 2.5 % and 5 % of the global population died, and nearly 20% were infected with the virus. The Influenza virus responsible for the deaths was an especially virulent or deadly strain of the same virus that causes flu outbreaks each year.

In 2003 another virus, called a coronavirus, caused an outbreak referred to as SARS for Severe Acute Respiratory Syndrome. Approximately 10% of the people who became infected with the virus died. Worldwide, over 750 people died. The outbreak disrupted travel and led to communities being placed in quarantine in order to control the spread of the disease; these measures may have helped keep the number of fatalities from being higher.

Infectious diseases can spread rapidly through a community as the bacteria or viruses responsible for the disease are passed from person-to-person. One of the primary means of controlling the spread of the disease is public education. If people know the symptoms and how the disease is transmitted, they can protect themselves from exposure and seek treatment quickly. Public service campaigns have often been used to educate people about diseases. What health-related public service campaigns do you remember?

For this project, you will work with a team to develop a public health campaign to prevent the spread of an infectious disease. You and your team will choose the disease and the advertising method for the campaign. The campaign can be a series of posters, a comic book, a video, a play or skit, radio announcements, a game, a puppet show, or any other means to educate the public about a disease. You will present your campaign to your classmates and other students as directed by your teacher.

Activity 7.1.1: What Are Medical Interventions?

Introduction

Did you take any medicine the last time you had a cold? Have you ever had surgery? Did you or someone you know ever have to wear a cast because a bone was broken? When you have a cut or scrape, do you put a band-aid on it?

All of those actions taken to treat an illness or injury (medications, surgery, casts, and bandages) are examples of medical interventions. An intervention is some action that is taken to change an outcome. A medical intervention is something that is done to treat or prevent an illness or injury. For example, imagine if someone broke a leg and the bone was not realigned and set in a cast. Would the outcome for that person be the same as if the leg was properly set in a cast?

The medical procedures and interventions that we take for granted today have not always been available. For example, the first antibiotic, penicillin, was not used to treat bacterial infections until the 1940’s. Before then, many people died from bacterial infections. Imagine dying from strep throat or from an open wound that developed yellow pus due to a bacteria called staphylococcus. Today, not only do we have several different antibiotics available to treat infections, many people even use soaps and wipes that are “anti-bacterial” because they contain drugs that kill bacteria.

The focus in this activity is on medical interventions that are considered the foundation and history of Western medicine because the medical system in the United States has its roots in Western medicine. The roots of Eastern or Oriental medicine can be found in China, Japan, and other countries in the Orient. Other medical histories or traditions include the American Indian, Arabic, and Armenian. After completing this activity, you may want to investigate these other medical traditions to see how they differ from Western medicine.

In this activity, you will determine what medical interventions were available at specific times in history. Follow your teacher’s instructions to prepare a PowerPoint presentation and present it to the class.

Project 7.1.2: How Are Medicines Developed and Tested?

Introduction

New medications, surgical techniques, and diagnostic methods are continually being developed. How are medicines developed and tested to be sure they are effective and safe to use? Just what is involved in bringing a new medication to the marketplace? Would you want to take a medicine that had not been tested and approved for sale?

It can take over 20 years to go from the initial testing or development of a medication until it is available to patients. During that time many safety and production issues must be addressed and solved. Less than 1 of every 5,000 potential medications actually becomes available to patients.

To complete this project, you will explore the pathway of pharmaceutical development and create a game that demonstrates the ups and downs along that pathway. The game should be designed for players aged 12 to adult and should focus on each of the steps involved in pharmaceutical development.

Activity 7.1.3: How Can Pharmaceuticals Help?

Introduction

Do you know anyone who is lactose intolerant? This person can not drink milk or eat ice cream without the potential for a severe abdominal upset. Usually when someone is lactose intolerant, he or she lacks the enzyme that normally breaks down the lactose molecule.

Lactose is a sugar found in milk. The lactose in a mother’s milk or in commercial infant formula is the primary source of energy for an infant. The lactose molecule is a disaccharide. (Remember disaccharides from Unit 3?) In order for the body to use the lactose sugar, it must be broken down into its component parts, glucose and galactose. This breakdown occurs with the help of an enzyme called lactase. People who are lactose intolerant either lack or have a decreased quantity of the lactase enzyme.

Remember in Unit 3 you investigated how energy is provided by food. You used a calorimeter to measure the amount of energy in food samples; you also read about and built models of different molecules, including glucose. Remember that cells obtain energy from glucose by the process of cellular respiration and the equation for this process is:

C6H12O6 + 6O2 → 6CO2 + 6H2O + energyRemember that C6H12O6 is the chemical formula for glucose; in the presence of oxygen, the glucose molecule is broken down to form carbon dioxide and water. In the process of breaking down the glucose, the energy is released from the molecule and converted to a form of energy the cell can use. Do you remember the name of the energy molecule produced by this process?

If a person can not break down a sugar molecule, such as lactose, that molecule can not be used as an energy source for that person. Additionally, if that molecule enters the large intestine, the bacteria there can use it as a source of energy. Bacteria break down the molecule, releasing gas and acids that cause discomfort for the person. That is what happens to someone with lactose intolerance. The person can not break down the lactose sugar; so it passes into the large intestine and the bacteria break it down, releasing gases and acids that make the person feel bloated and have abdominal pain.

If the lactose is broken down before it gets to the large intestine, then it can not be used as an energy source by the bacteria and no gases or acids are produced. That is why people with lactose intolerance take a pharmaceutical that contains the enzyme lactase and is sold without a prescription. The pill contains the lactase enzyme the person lacks. The lactase enzyme breaks down the lactose sugar before it can reach the bacteria in his or her large intestine. Once the lactose sugar is broken down by the enzyme in the pill, the energy in the sugar can be used by the person instead of by the bacteria. Plus, all the side effects caused by the bacteria using the sugar are eliminated.

You will test the activity of a pharmaceutical that contains lactase and is sold to people with lactose intolerance. Because we can not run these tests using lactose intolerant people, we will use yeast cells. There are many types or species of yeast that people use to make cheese, bread, pizza dough, and beer. All yeast strains are single-celled organisms that are often confused with bacteria. However, yeast cells are much more like human cells than bacterial cells. Additionally, most yeast strains lack the lactase enzyme, including Saccharomyces cerevisiae, the yeast commonly used to make bread. Therefore, we can use yeast as a model of a lactose intolerant person. If a yeast species can use a sugar molecule as an energy source, carbon dioxide gas will be released because the process of cellular respiration is the same in yeast cells as it is in human cells. Consequently, we can measure the amount of carbon dioxide produced by yeast cells to indicate whether or not the sugar is being used for energy.

In this activity, you will test whether a pharmaceutical can alter the ability of an organism’s cells to use a molecule as an energy source. You will measure the production of carbon dioxide to determine the ability of the yeast Saccharomyces cerevisiae to use various molecules for energy including: water, glucose, whole milk, or whole milk treated with a pharmaceutical that contains lactase.

Problem 7.1.4: What Medical Interventions Might Have Helped?

Introduction

Throughout this course you have been studying diseases and conditions that the autopsy results in the first unit indicated the fictional dead victim had. You determined that the cause of death was a heart attack, but all the other health conditions also impacted her health and ultimately her ability to survive. She was diabetic and had further complications due to sickle cell disease, high cholesterol, and past bacterial infections. Because the body is a system and all the components work together, it is not uncommon for a patient to have multiple medical issues or complications. All of her medical conditions affected the ability of her heart to function properly.

Think back to the results of her autopsy that you combined into the evidence board in Activity 1.1.8. Remember that there was evidence of several medications in her blood including thiazolidione, piolitizone, acetylsalicylic acid, and hydroxyurea. These medications were pharmaceutical, medical interventions prescribed by her physician to prolong her life.

In this activity, you will be assigned one of the victim’s medical conditions. Your task will be to research the medical interventions prescribed by the victim’s physician and to determine if other interventions are available or in development for the assigned medical condition. You will write a report for submission to the victim’s physician. The report will be used to evaluate the treatment given and to learn if newer treatment options are available.

Activity 7.1.5: What Is Biomedical Engineering?

Purpose

Imagine what health care would be if there were no x-ray machines, no CT scans, no motorized wheelchairs, no pacemakers, and no minimally invasive robotic-assisted surgery! All of these products are available because engineers designed and developed them.

Biomedical engineers specifically work at the junction of the biomedical sciences and engineering. They examine the structures and processes that occur in the human body. Bioengineers design products to enhance body function and correct problems that can occur. The human body performs a vast array of tasks including moving from place to place; transporting, distributing, and recycling of materials; building and repairing tissues; and obtaining energy. As scientists and bioengineers study each of these tasks, they learn the processes that underlie healthy function and use that knowledge to design products that may improve a person’s health either with better diagnostic tools, improved body function, or even replacement of body parts.

Bioengineers use the principles and processes involved in all aspects of engineering and apply them to design and develop products for living organisms, including humans. Because the field of bioengineering includes all the aspects of multiple areas of engineering, it is divided into many areas of specialization, each representing a specific relationship to the other areas of engineering. For example, a bioengineer may specialize in biomaterials. This individual is applying all the concepts of materials science to produce materials that are compatible with living organisms. In order to design an artificial hip joint for hip replacement surgery, the biomaterials engineer must ensure the materials used to make the artificial joint will last in the body, not harm it, and allow the joint to move properly while still supporting the body.

In this activity, you will be part of a team that investigates a specific medical product that was produced as a result of biomedical engineers working with scientists, physicians, and other engineers. As you research your assigned product, look for connections between the fields of engineering and the biomedical sciences and determine how the product improves the health and quality of life of a patient. As you research, think about the technology involved in the design, testing, and production of the medical product.

Problem 8.1.1: A Call for Grant Proposals—What Can We Do?

Introduction

Your experience with Biomedical Science has expanded and you have a greater understanding of the broad spectrum of topics and careers related to Biomedical Science due to your participation in the Principles of the Biomedical Sciences course. Scientific research is a vital component of the Biomedical Sciences and grant funds are needed for this research to continue.

Infectious disease is the leading cause of death worldwide today. Even in the U.S., it is one of the top five leading causes of death. Many of the pathogens causing these diseases are becoming resistant to current drugs and, in rare cases, completely immune to known treatments. Antibiotic resistance has made it imperative that research and development continue in the area of pharmacology.

In 1971, during the State of the Union Address, President Richard Nixon asked for $100 million to fight the “war on cancer.” Over 25 years later, cancer remains the second or third leading cause of death in the U.S. with 1.2 million Americans diagnosed with it each year. The good news is

more people are living longer than ever before after the initial diagnosis of cancer. This is because research has resulted in better treatments. That said, cancer is still the leading cause of death in children between the ages of one and fourteen in the U.S. and ten percent of all medical dollars are spent on cancer. Much more progress is needed.

The leading cause of death in the U.S. is heart-related disease. Ten million people in the U.S. suffer from heart failure every year. Although more of them survive today than even ten years ago, the numbers indicate heart disease is still a major issue. These are just a few examples of issues the medical community deals with on a daily basis. Research is essential for continued progress in solving these problems, and research is dependent upon grants.

The National Institutes of Health (NIH), the Center for Disease Control (CDC), and the National Institute of Allergy and Infectious Disease (NIAD) are just three of the hundreds of agencies that conduct biomedical research along with countless private companies and industries. All of these entities fund researchers through the grant process.

In this project, you are part of a biomedical research team applying for grant funds to research and provide a positive impact on a specific disease or medical condition. For this project, you will complete an abbreviated version of an actual medical grant. Choose a topic your team finds interesting and would like to know much more about. The topic must be something that has not been researched earlier in this course. Imagine yourself as a real medical specialist trying to find a cure or treatment for a disease. Your research is dependent upon your grant proposal being chosen for continued funding. Your team’s work will be presented in both written and oral form to an advisory panel.