Reporting Category 1 Tier 3

Biological Molecules What are the building blocks of life?

Why? From the smallest single-celled organism to the tallest tree, all life depends on the properties and

reactions of four classes of organic (carbon-based) compounds—carbohydrates, lipids, proteins, and

nucleic acids. These organic molecules are the building blocks of all living things, and are responsible for most of the structure and functions of the body, including energy storage, insulation, growth, repair,

communication, and transfer of hereditary information. Simple organic molecules can be joined together to form all the essential biological molecules needed for life.

Model 1 – Molecules of Life

1. Use Model 1 to show which atoms are present in each type of molecule by listing the symbol for each atom included. Carbohydrate has been done for you.

a. Carbohydrate — C, H, O

b. Amino acid —

c. Lipid —

d. Nucleic acid —

2. Which type of molecule includes an example with a long-chain carbon backbone?

3. In the molecule referred to in the previous question, what is the dominant element attached to the carbon backbone?

4. The fatty acid chain of the lipids is often referred to as a hydrocarbon chain. Discuss with

your group why the chain is given this name and write a one-sentence defi nition for a

hydrocarbon.

5. Which molecule has a central carbon atom with four different components around it?

6. Which molecule has a sugar, nitrogenous base, and phosphate group?

7. Discuss with your group members some similarities among all four types of molecules. List as many as you can.

8. What is the chemical formula of the fi rst carbohydrate molecule shown?

9. What three structural groups shown do all amino acids have in common?

10.There are 20 naturally-occurring amino acids, and each one only varies in the structure of

the R side chain. Two amino acids are shown in Model 1. What are the R side chains in

each?

Read This! During chemical reactions, the bonds in molecules are continually broken and reformed. To break a bond, energy must be absorbed. When bonds are formed, energy is released. If more energy is released than

absorbed during a chemical change, the process can be used as a source of energy. A general rule for processes such as respiration is the more carbon atoms there are in a molecule, the more energy that

molecule can provide to the organism when it is used as food.

Model 2 – Biochemical Reactions

11.What are the reactants of reaction A?

12.What are the products of reaction A?

13.Each of the reactants in reaction A is a single sugar molecule, also called a

monosaccharide. What prefix before saccharide would you use to describe sucrose?

14.What are the reactants of reaction B?

15.When the two molecules in reaction B are joined together, what other two molecules are produced?

16.What product do all three reactions in Model 2 have in common?

Extension Questions

17.Metabolism is the collective term used to describe all the chemical reactions taking place inside living organisms. Why is water so important for metabolic reactions?

18.We store excess food in our body either in the form of carbohydrates (in muscles and the

liver) or as fat (adipose tissue). When our body needs additional energy it uses the

carbohydrate source first as a source of ―quick‖ energy, then the fat. Why do you think carbohydrates are used as a source of quick energy rather than fat? Use complete

sentences and scientific terminology in your response.

19.Look at the two types of fatty acids below, saturated and unsaturated. What is the

difference between the two?

20.Saturated fats are solid fats, like the animal fats lard and butter, whereas unsaturated fats

are more fluid and form oils, such as vegetable oil. Trans fats are plant oils that are

artificially solidified to make them suitable for baking purposes. In recent years trans fats have been associated with negative health issues and are not as widely used. Explain in

simple molecular terms what would have to be done to a plant oil to transform it to a

trans fat.

Viruses In 1935, the American biochemist Wendell Stanley isolated a virus for the first time. Viruses have two

methods of infection once inside a host cell.

1. What is a bacteriophage?

2. What are viruses?

3. What is a capsid?

4. How does a typical virus get inside a

cell?

5. What occurs when viruses get inside

cells?

Organelles in Eukaryotic Cells What are the functions of different organelles in a cell?

Why? The cell is the basic unit and building block of all living things. Organisms rely on their cells to perform all

necessary functions of life. Certain functions are carried out within different structures of the cell. These structures are called organelles.

Model 1 – How Is a Cell Like a Factory?

Part of Factory Cell Organelle Function

Control room (E) Nucleus Contains and protects genetic material

(DNA)

Factory manager DNA/chromosomes Information for making proteins

Assembly workers (F) Ribosomes Make proteins

Production line (B) Endoplasmic reticulum

(ER)

Transports and finishes proteins and

other biological molecules

Custodians (A) Lysosomes

Power generators (H) Mitochondria

Shipping department

(C)

Golgi apparatus

Factory interior Cytoplasm Space for work to be done

Items to be shipped Vesicles Cellular package containing products

such as protein

Warehouse for storage

of products

Vacuole

Loading dock Pores/gated channels Points of entry and exit for materials

Security fence (D) Cell membrane

1. Using the letters from the table in Model 1, label the cell diagram with the organelle

names.

2. According to the table,

a. what substance is analogous to a factory manager?

b. in what organelle would this substance be found?

3. Using the information in Question 2, which cell organelle controls the activities of the entire cell?

4. Which organelle generates energy to power cellular activities?

5. Which organelle is responsible for assembling proteins?

6. Once proteins have been assembled, to which organelle would they go next?

7. Into what organelle might the cellular products be placed?

8. Fill in the missing functions of cellular organelles in the table in Model 1.

9. Starting with instructions from the factory manager (DNA/chromosomes), create a fl ow

chart to show how a protein is produced and shipped from a cell.

Membrane Structure and Function How do substances move in and out of cells?

Why? Advertisements for sports drinks, such as Gatorade®, PowerAde®, and Vitaminwater™, etc. seem to be everywhere. All of these drinks are supposed to help your body recover and replenish lost electrolytes,

fluids, and vitamins after exercise. But how do the essential molecules contained in these drinks get into your cells quickly to help you recover after exercise?

Model 1 – Simple Diffusion

1. How many different types of molecules are shown in Model 1?

2. Count and record the number of triangles and circles found on each side of the

membrane.

3. Which shape is larger?

4. Describe the direction of the movement of the molecules in Model 1?

5. Which molecules are able to pass through the semi-permeable membrane? Justify your

answer.

6. If you left this ―system‖ for an extended period of time and then viewed it again, would you expect to find any changes in the concentrations of the molecules on either side of

the membrane? Justify your answer.

Transport in Cells How do water molecules move in and out of cells?

Why? Water accounts for over 70% of the human body. If water levels are not regulated and maintained in an organism the consequences can be disastrous. Cells and tissues may swell, blood cells burst, or the brain

may expand so much it pushes on the skull, leading to brain damage and death. So what exactly is the process that allows organisms to regulate and maintain their water content?

Model 1 – Movement of Water In and Out of Cells

1. A solution consists of a solute and a solvent mixed together. For the solution in Model 1 identify and provide the symbol for the

a. solute.

b. solvent.

2. Consider the size of the sugar and water molecules in Model 1. Which molecules in the

diagram in Model 1 are able to move through the selectively permeable membrane?

3. Complete the table below by counting the molecules in Model 1.

Inside the Cell Outside the Cell

Number of sugar molecules

Number of water molecules

Ratio of water to sugar

4. Which solution in Model 1 is more concentrated—the solution inside the cell or outside of

the cell? Explain your answer in terms of the ratio of solute to solvent particles.

5. Consider the arrows indicating movement of water across the membrane.

a. In which direction are water molecules moving—into or out of the cell?

b. Are more water molecules moving into or out of the cell? c. Is the net direction of water movement into or out of the cell?

6. Choose the correct word below to indicate the change in the concentration of the sugar

solution on each side of the membrane as water molecules move.

a. The solution inside the cell will become (more/less) concentrated with the net movement of water.

b. The solution outside the cell will become (more/less) concentrated with the net

movement of water.

7. Applying what you already know about the random movement of molecules, what will eventually happen to the concentration on both sides of the membrane?

8. The definition of diffusion is the movement of molecules across a membrane from an

area of high concentration to an area of low concentration. According to this definition, is

the cell in Model 1 undergoing diffusion? Explain.

9. In the cell diagram in Model 1, where is the higher concentration of water—inside or

outside of the cell?

10.Is the cell in Model 1 undergoing diffusion if you consider the concentration of water on

either side of the selectively permeable membrane? Explain.

Read This! Osmosis is the movement of water from high water concentration to low water concentration across a

semi-permeable membrane.

Extension Questions

11.Using the concept of osmosis, explain why water is sprayed over produce in a grocery

store. How might this change the appearance of the produce, and why would this change

be desirable?

12.Suppose you made a lettuce salad in the afternoon, added salt and other seasonings, and

then put the salad in the refrigerator. When you took the salad out of the refrigerator for

dinner, the lettuce looked wilted and some water was in the bottom of the bowl. Use the

principles of osmosis to explain what happened.

13.In extreme cases, it is possible to die from drinking

too much water. The consumption of several liters

of water in a short amount of time can lead to brain

edema (swelling) and death. Explain the effect of

ingesting an extremely large amount of water at the level of the brain cells, including the role of

osmosis in this process.

14.The diagram to the right shows a single-celled

organism called Paramecium, which lives in freshwater environments. This organism contains a

specialized organelle called a contractile vacuole

that helps maintain osmotic balance. Predict how

this organelle might help the organism survive

given that it is constantly immersed in a hypotonic

solution.

DNA Structure and Replication How is genetic information stored and copied?

Why? Deoxyribonucleic acid or DNA is the molecule of heredity. It contains the genetic blueprint for life. For

organisms to grow and repair damaged cells, each cell must be capable of accurately copying itself. So

how does the structure of DNA allow it to copy itself so accurately?

Model 1 – The Structure of DNA

1. Refer to the diagram in Model 1. a. What are the three parts of a nucleotide?

b. What kind of sugar is found in a nucleotide?

c. Which nucleotide component contains nitrogen?

d. Name the four nitrogen bases shown in Model 1.

2. DNA is often drawn in a ―ladder model.‖ Locate this drawing in Model 1. a. Circle a single nucleotide on each side of the ladder model of DNA.

b. What part(s) of the nucleotides make up the rungs of the ―ladder‖?

c. What parts of the nucleotides make up the sides (backbone) of the ―ladder‖?

d. Look at the bottom and top of the ―ladder‖ in Model 1. Are the rungs parallel (the

ends of the strands match) or antiparallel (the ends of the strands are opposites)?

3. On the ladder model of DNA label each of the bases with the letter A, T, C or G.

4. Refer to Model 1. When one nucleotide contains adenine, what type of base is the adenine

attached to on the opposite nucleotide strand?

5. The two strands of DNA are held together with hydrogen bonds between the nitrogen

bases. These are weak bonds between polar molecules. How many hydrogen bonds

connect the two bases from Question 4?

6. Refer to Model 1. When one nucleotide contains cytosine, what type of base is the

cytosine attached to on the opposite nucleotide strand?

7. How many hydrogen bonds connect the two bases from Question 6?

8. With your group, use a complete sentence to write a rule for how the bases are arranged

in the ladder model of DNA.

Read This! Erwin Chargaff (1905–2002), an Austrian-American biochemist, investigated the ratio of nucleotide bases found in the DNA from a variety of organisms. From his research, as well as research by Rosalind Franklin

and Maurice Wilkins, Watson and Crick developed the complementary base-pair rule during their race to discover the structure of DNA. The complementary base-pair rule states that adenine and thymine form

pairs across two strands, and guanine and cytosine form pairs across two strands.

9. Fill in the complementary bases on the strand below according to the base-pair rule.

A T C C A G

10.The ladder model of DNA is a simplifi ed representation of the actual structure and shape

of a DNA molecule. In reality, the strands of DNA form a double helix. Refer to the

double helix diagram in Model 1 and describe its shape using a complete sentence.

Model 2 – DNA Replication

11.Examine Model 2. Number the steps below in order to describe the replication of DNA in a

cell.

a. Hydrogen bonds between nucleotides form.

b. Hydrogen bonds between nucleotides break.

c. Strands of DNA separate.

d. Free nucleotides are attracted to exposed bases on the loose strands of DNA.

12.Locate the DNA helicase on Model 2.

a. What type of biological molecule is DNA helicase?

b. What is the role of DNA helicase in the replication of DNA?

13.What rule is used to join the free nucleotides to the exposed bases of the DNA?

14.This type of replication is called semi-conservative replication. Considering the

meaning of these words (semi—half; conserve—to keep), explain why DNA replication is called semi-conservative.

15.DNA molecules can be tens of thousands of base pairs in length. Mistakes in DNA

replication lead to mutations, which may or may not be harmful to an organism. How does

semi-conservative replication help prevent mutations during DNA replication?

16.The proportions of the bases are consistent within a species; however they do vary

between species. Using the base-pair rules, complete the following table to show the

percentage of each type of base in the five different organisms.

Organism

Percentage of each type of base

Adenine

Guanine

Cytosine

Thymine

Human 31 19

Cow 28 22

Salmon 21 29

Wheat 27

Yeast 31 19

The Cell Cycle What controls the life and development of a cell?

Why? An old piece of poetry says ―to everything there is a season... a time to be born, a time to die.‖ For cells,

the line might say ―a time to divide and a time to grow.‖ In multicellular organisms, different types of cells

have different roles and need to complete specific tasks. For example, a cell that isn’t large enough is not useful for storing nutrients for later, but a cell that is too large will not be useful for transportation through

a tiny capillary. In this activity, you will learn about the seasons of a cell’s life, and in turn better

understand how organisms function.

Model 1 – The Cell Cycle

1. How many phases are in the cell cycle as shown in the diagram in Model 1?

2. Starting at the starred cell, what is the order of the stages of a cell’s life?

3. During which phase does the size of the cell increase?

4. During which phase does the number of cells increase?

5. Considering your answer to Questions 3 and 4, identify two ways that the growth of an

organism can be accomplished through the events of the cell cycle.

6. Cancer, the uncontrolled growth of cells, often results in a tumor, or mass of abnormal

cells. Some cancerous tumors consist of many cells that are much smaller than normal.

According to Model 1, what part(s) of the cell cycle is (are) most likely being affected?

7. In Model 1, if the length of the arrow represents time, then for those cancerous cells,

what happens to the time that is necessary for the cell cycle? What implication might this

have for doctors who are treating cancer patients?

Model 2 – Cell Cycle Data

Phase Key Process Time

Interval (hours)

Sets of DNA

present in each cell at

end of phase

Number of

organelles in each cell at

end of phase

Gap1 11 1 560

Synthesis 8 2 570

Gap2 Protein and organelle synthesis 4 2 600

Mitosis Cell and nuclear splitting 1 1 300

Total time: 24

8. Model 2 presents cell cycle data for a typical human cell in culture. Use the phase names

in Model 2 to label the G, M, and S phases in Model 1.

9. Looking at the third column of Model 2, compare the time spent in mitosis with the time

spent in gap1 in human cells and describe any difference.

10.Imagine 100 cells were chosen randomly from a tissue sample and examined under a

microscope. In which phase of the cell cycle would you expect to fi nd the largest number

of cells? Explain.

11.Look again at Model 2. Compare the amount of DNA at the beginning and end of

synthesis. Why did the amount of DNA change?

12.Fill in the ―Key Process‖ column for synthesis phase in Model 2.

13.Cyto = cell, kinesis = cutting. What do you think takes place during cytokinesis?

14.Other than cytokinesis, what else occurs during the mitosis phase? Hint: Consider the sets

of DNA in each cell.

15.Look carefully at information given to you in Model 1 and Model 2. Fill in the key process

column in the table for gap1.

16.If a culture in the lab starts with one human cell, how many cells will there be after 24 hours?

17.The total time for the phases listed in Model 2 is 24 hours. How many human cells will be

in the culture after another 24 hours? Explain.

18.Is the original cell ―dead‖ or does it disappear after mitosis? Explain your answer.

19.If a starfi sh sustains damage to a limb, it often grows a new one. If a human adult

sustains damage to his or her spinal cord, mobility is often impaired. If a gecko loses its

tail, it may grow a new one. Which type of cell is less likely to go through the cell cycle

after being damaged—starfi sh limb, human spinal cord, or gecko tail? Support your answer.

20.Occasionally cells stop dividing and enter another phase, G0. If you damage your liver,

new liver cells can be produced to replace up to 75% of the liver. However, if you sustain

brain damage, your body does not produce new brain cells. Explain this observation using what you have learned about the cell cycle.

21.Keeping in mind the events of each part of the cell cycle, mark with a double arrow on

Model 1 where those cells might (either temporarily or permanently) exit the cell cycle to

G0. Label this as G0. Why did you choose this location for G0? Hint: Think of a place in the cell cycle where the cell is functioning normally, but not preparing to divide.

22.Consider a cell in G0. Use the information in both Models 1 and 2 to answer the following

questions.

a. In order for this cell to divide normally, what would need to occur? b. What if the phase(s) you identifi ed in part a of this question did not occur? What

would be the outcome for the cell in that case?

Extension Questions

23.For each phase, describe at least one way mistakes during the cell cycle could result in

problems. a. G1

b. S

c. G2

d. M

e. G0

24.Some types of cancers are treated with radiation, similar to ultraviolet light. Why might it

be beneficial to irradiate cancer cells?

25.Plasmodial slime mold is an example of a multinucleated cell. It can be

referred to as ―one huge cytoplasmic mass with many nuclei‖ as seen to the right. What part of Model 1 is skipped in the formation of such a

cell? Explain your answer.

26.Chemotherapy utilizes chemicals that disrupt various parts of the cell

cycle, targeting rapidly growing cells. Paclitaxel (Taxol®) is one such drug that prevents the mitosis phase from taking place.

a. Explain how this drug is useful as a cancer treatment.

b. How might targeting rapidly growing cells explain common

chemotherapy side effects such as hair loss and nausea?