Chapter 7Adventures in Bodybuilding

No, we don’t mean Mr. or Ms. Universe body-building. What we mean is, how did multi-cellular bodies originate?

Adventures in body building

• Much of what makes a body is locked inside the cell.

• Bodies looks the way they are because of the way cell the way they are attached to one another, the way they communicate, and the different materials they make.

• To make all of a body’s tissue and structures, cells know how to cooperate, to come together to make an entirely new kind of individual

• To address how did bodies arise, when they came about and why did bodies arose, we need to look at the basic structures of cells

Organisms cells come in two basic forms.

• Single celled organisms - Prokaryotes (Bacteria)

• Multi-cellular organisms – Eukaryotes ( Animals and Plants).

Most every organism we see in our day-to-day lives are Eukaryotes (trees, mushrooms, ants, flies, dogs, people)

All eukaryotes multi-cellular and all have membrane bound organelles.

Organelles – functional intercellular small organs inside the cell

Bacteria Cell

Organelles and their Functions

• Nucleus• Mitochondria• Ribosomes• Rough endoplasmic reticulum• Smooth endoplasmic reticulum• Lysosomes• Golgi apparatus

• Houses DNA for reproduction• Produces energy (ATP)• Produces proteins• Fold and modify proteins• Produces Lipid hormones• Cleaning agent• Storage of proteins and lipids

Adventures in body building

• There is a division of labor between parts of the cell• The division of labor extends from cells-tissues-organ-organ system-

whole organism.• Four Types of Tissues in the Human Body• Epithelial: lines body surfaces and cavities• Connective: supports and bonds body parts• Muscular: moves the body and its parts• Nervous: receives stimuli and conducts impulses

The Cell Cycle

Reproduction by Mitosis Process

• Interphase – DNA Duplication• Prophase-nuclear membrane disappears, centrosomes migrate,

spindle fibers appear• Metaphase-chromosomes line up at metaphase plate, associated

with spindle fibers• Anaphase-centromeres divide, sister chromatids migrate to opposite

poles, cytokinesis begins• Telophase-nuclear membranes form, spindle disappears, cytokinesis

occurs

Meiosis Process

Adventures in body building

• This division of labor continues like a river that remains the same despite changes in its course, we remain the same individual despite the continual turnover of our parts.

• If the different parts of bodies break down, the individual creature can die.• A cancerous tumor is born when a single cells genetically becomes

unstable. And break the rules that allows cells to cooperate with one another

Cancer: A Failure of Genetic Control

• Apoptosis – programme cell death

• Proto-oncogenes promote the cell cycle and prevent apoptosis.

• Tumor suppressor genes prohibit the cell cycle and promote apoptosis.

Cancer: A Failure of Genetic Control

• Contact Inhibition: When cells come into contact with neighboring cells, they stop dividing. • Cancer cells lose contact inhibition and form tumors.• The tumor is deemed noncancerous or benign if it stays as a single

mass.• Cells are called cancerous when they invade surrounding tissues.• Cancer cells can travel through the bloodstream and the lymph and

develop into secondary tumors.• Metastasis refers to cancer cells that have spread to other parts of the

body.

Cancer: A Failure of Genetic Control

Characteristics of Cancer Cells• Cancer cells are genetically unstable.• Cancer cells do not correctly regulate the cell cycle• Cancer cells escape the signals for cell death.• Cancer cells can survive and proliferate elsewhere in the body.

Adventures in body building

• For single cells to survive they needed to create new mechanism to work together.• They needed to able to communicate with one another• They needed to stick together in new ways.• And they needed to be able to make new things, such as molecules

that make our organs distinct.• Your author gives an analogy : What happens when you take some

bacteria from a mat of bacteria? You end up with a smaller mat of bacteria. But what happens if you remove some cells from a human, say from the heat or brain, you could end up with a dead human.

From single cell to multicellular

It is well known that life on earth appeared between 3 billion and 3.8 billion years ago. There is some debate about when multicellularity arose, but it was probably sometime between 1.5 and 1.8 billion years ago. Again, that’s the earliest evidence that we have found, not the actual start of multi-cellular life.

Look at the figure on page 121.

Energy – the driving force of life

• There is one very important reason that there isn’t much evidence of multi-cellular life before then.

• It has to do with energy.

• Multi-cellular bodies are big energy hogs. One portion of the body has to generate enough fuel to power all of the cells in the body.

• Think of a tree with that huge canopy to provide sugar to all the cells that can’t photosynthesize. And that tree doesn’t have to move or keep itself warm.

• Other bodies that move, hunt, and keep themselves warm even when the outside (the body) temperature is below freezing have to use a lot of energy.

Oxygen—the making of Energy

• Without oxygen, that level of energy just isn’t available.

• A cell that can use oxygen to make energy usable can produce almost 20 times the amount of useful energy as cell without oxygen.

• Organisms with multiple cells, if there are too many cells that can’t get to the incoming food and there’s no way to transport the food to the interior cells, then the cells on the inside die.

Aerobic Cellular Respiration

Chapter 8Receptors and Sensations

• Types of Receptors• Chemoreceptors• Taste, smell

• Photoreceptors• Vision (light)

• Mechanoreceptors• Hearing, gravity, motion, body position

• Thermoreceptors• Temperature

Chapter 8Making Scents

• The opening of this chapter gives us a simple experiment that anyone can do at home and see DNA for perhaps the first time ever. I’ve done this in the lab, and while I haven’t done in the kitchen, the steps we used in the lab were exactly the same (except for some fancier chemicals than meat tenderizer and dish soap). You can actually see DNA (en masse) in your own kitchen. The steps are easy.

Making Scents

1. Take a steak or some peas or anything else for that matter add salt water and set your blender to “liquidfy”. This will disrupt the cells and make the insides of the cells available to us.2. Add some dish soap (non-lotion). This will break up the cell membranes that are too small for the blender.3. Add some meat tenderizer (un-flavored). This will break up the

proteins that hold the DNA.4. Gently mix in some rubbing alcohol. The DNA is attracted to the

alcohol (chemically speaking).

Making Scents

• You should get two layers in your container. A layer of soapy water at the bottom and a layer of rubbing alcohol at the top. If you got a white ball in the rubbing alcohol, then you did it right. That white ball is pure DNA. If you are very careful, you can bend a paperclip, stick it into the ball of DNA and pull it out.

• Congratulations, this is the basic step of genetic test and sequencing experiment ever done.

• Why is this important to our sense of smell?

Making Scents

• Humans have pretty good noses. The best among us can identify 10,000 unique odors. Some can pick out certain scents at 1 part in a trillion. That’s like picking out a single dollar bill out of one trillion. (And in this example, there are 100 sets of that (since those are $100 dollar bills)).• Scent works kind like a puzzle. Each chemical that we can smell has a

unique shape and/or chemical attributes. • We have proteins receptors in the cells of our nose that matches those

chemical perfectly. Then one of those chemicals latches onto the protein, the protein causes a signal to be sent to the brain. This signal tells our brain that the chemical has been detected and our mouth waters, or we vomit, or we remember grandma’s kitchen.

Making Scents

• Now here’s the neat bit: 3% of our entire genome is dedicated to these receptor proteins. In other words, 3% of our entire genome is dedicated to the sense of smell.

• Now each chemical has two different proteins that respond to it. • One for the chemical in air and another for the chemical in water.

Interestingly, fish have only water sensing proteins while land animals have only air sensing proteins and amphibians… well, they have both.

Making Scents

• It gets even better. The researchers who found all those scent genes also discovered that, much like other genes and traits, they can be tracked via the mutations in them. • Because they are so specific to chemicals, there is a limited amount of

change that can occur in the gene before the ability to scent something is lost.

• Humans have lost over 300 scents due to mutations in those scent genes. They are in the right place, the genes are just broken. Amazingly, creatures that would seem to be more closely related to humans have lost the same scent genes in the same ways (the same mutations).

Chapter 9 – Vision

• All our eyes do is gather light and focus the light onto the retina receptors. The retina is full of special photo receptor cells called rods and cones. • These rods and cones are specialized light absorbing photo receptor

cells, each responding to certain forms of light and sending nerve impulses to the brain. • The brain then interprets the pattern of nerve signals into what we

think of as an image.

Type of Eyes

• Camera-type eyes• The human eye is an example of a camera-type eye, which uses a

single lens to focus images onto a light sensitive membrane lining the inside of the eyeball called the retina. Other camera-type eyes exist in nature as well, and some of them are capable of doing neat tricks that our own eyes can't.• Compound eyes• The type found in insects and arthropods, compound eyes are made

up of many individual lenses. In dragonflies, for example, a single compound eye can have as many as 10,000.

Opsins

• The molecules that actually absorb the light energy and covert that to a electrical impulse which can start a nerve transmission are proteins called opsins.• Opsins are found in almost all organisms on the planet. Humans, insects,

clams, and scallops all use.

• Majority of mammals have two genes for color vision and the higher primates (yes, including humans) having three.*

• Humans have three genes for opsins production, giving us a very large range of color vision.

Vision Genes

A gene called Pax6 controls vision.• With some creative genetic engineering, researchers found that Pax6

could be used to grow an eye in fruit flies (again, anywhere the researchers wanted), but it was still a fruit fly eye.• This gene, either in a fly and one in a mouse, were so similar that

either of them can trigger the complex developmental cascade that results in the formation of an eye.

Chapter 10: Sense of Hearing

• The Ear Has Two FunctionsHearing and Balance

• Mechanoreceptors (hair cells) located in the inner ear are associated with both functions• The ear is made up of three different sections: the outer ear, the

middle ear, and the inner ear. • These parts all work together so you can hear and process sounds.

Maintaining Balance

• Ears do more than hear. They keep you balanced, too. In the inner ear, there are three small loops above the cochlea called semicircular canals. Like the cochlea, they are also filled with liquid and have thousands of microscopic hairs.

• When you move your head, the liquid in the semicircular canals moves, too. The liquid moves the tiny hairs, which send a nerve message to your brain about the position of your head. In less than a second, your brain sends messages to the right muscles so that you keep your balance.

Effects of Alcohol on Balance

• One of the effects of having a high blood alcohol level is that the inner ear system that keeps you balanced gets screwed up and you stagger around like an idiot for a day or so. The reason is that the alcohol from your blood stream goes into your inner ear canals and displaces the fluid that is used in your balance system. That movement of the fluid as it is displaced is sensed by the nerve cells and is reported to the brain as movement… when you aren’t moving.

• The reverse happens the next morning. Your liver has removed most of the alcohol from the blood, and the alcohol in your inner ear slowly diffuses back into the blood stream. The inner ear fluid moves back to where it’s supposed to be and your ear reports that as movement too.****

Genes and Hearing

• A gene called Pax2 controls the development of the inner ear. • A mutation of this gene results in a badly formed or missing inner ear.

Adventures in Bodybuilding

• We are extremely specialized, to the point none of our cells can long survive without the others.

• Now, what’s really interesting, is that the some of the materials that we use to hold our bodies together are found in bacteria. Those proteins that hold us together have been around for almost the entire history of life on this planet.