Bare Bones Biology 010 Transcript

Evolution Terms

Before we go further on the subject of genetics and evolution, let’s make sure we are all using the same words to mean the same things. You don’t need to remember these words; if you are still interested when we finish today, you can check the transcript that will be posted on Wednesday.

We already talked last time about biological evolution. It is a change in the gene pool over time.

A gene pool is all the genes in a species or other group of interbreeding animals. A species is a group of organisms that do or can interbreed. That’s like all the dogs, or all the cats, all the people, or all Post Oak trees, and that sort of thing. All the organisms in one species share a gene pool. The gene pool is all the genes that could be passed on because all members of the gene pool are capable of breeding together. Whether or not they do.

A gene is a unit of function that can be passed on to the next generation. Every gene has one function (OK, there are exceptions). Almost every gene has one function inside a cell or inside your body. Usually the function of a gene is to code for a protein that does the actual function. For example, there is a gene and a protein that have the same name, that is tyrosinase, and the function of the protein is to make pigment in your pigment cells. That’s it. Genetics at its bare bones really is that straightforward. Each gene makes a protein and each protein has a function. And the genes are physical entities, they’re molecules that can be copied and transferred to the next generation.

The functions of the genes result in real traits in the organism. I am looking right at you and you do have pigment in your eyes, your hair and your skin. You have pigment in your pigment cells, and I happen to know what gene is responsible for the enzyme in pigment cells that causes pigment to be made. That would be, tyrosinase. Your pigment is normal, therefore your tyrosinase protein is normal, therefore your tyrosinase gene has a normal genotype. If your tyrosinase gene were not normal you would have an albino phenotype. The phenotype is your physical trait that results from a certain genotype. The genotype describes whether or not your gene or genes that control a particular trait are normal. Every different kind of gene controls a specific function that regulates a specific trait.

All of your genes together — all the genes together, all the different kinds of genes, control all the inheritable traits in your body — these are your genome. Your genome is all the genes in your body. This is different from the gene pool that is all the genes in all the bodies of the same species. I will use the word phenome to describe all of your phenotypes that result from your genome — you are a person with black hair and brown eyes and a short chin and a certain size and so and so and so.

All of the genes in a whole species, all humans for example, is the gene pool. The gene pool is associated with the physical characteristics of the whole species, another example, a certain species of spider is an animal that is of a particular shape and color and builds a certain kind of web to catch its food. All the inheritable physical characteristics of this species are associated with the genes in the whole gene pool.

The evolution of the whole ecosystem is based on the relationships between and among the gene pools of all the different species that make up the whole living earth ecosystem. This is the most important ecological concept that I know, and as far as I know it does not have a name.

Shall we name it?