![]() The genotype is basically the info in the DNA, and every cell in your body has got all the information in it that is needed to build a whole organism. So there’s a general principle here that’s quite intriguing and it has to do with how you turn information into matter. Now, how does this relate to organisms? Well that’s the issue of genotypes and phenotypes, and that’s a question of information and matter. So we’re not talking about tiny, weensy, little molecules. When I first isolated DNA from sugarcane, and condensed it in ethanol, it came out, in the ethanol mixture, as a bunch of white, stringy strands, and I could wrap it around a glass rod. ![]() So just chop this piece of measuring tape up into 26 pieces and you get about the size that you’ve got in each of your chromosomes. So when they say it is a macromolecule, it is a serious macromolecule. If you were to put all the chromosomes in your nuclei together, and just for one cell, and string them together, one haploid copy is exactly one meter long. You can think of that as letters forming words. The sugar phosphate backbone is the same in every DNA molecule on the planet, and the information in the molecule is in the sequence of nucleotides. The sugar phosphate strands form the backbone, and then the nucleotides are glued onto the backbone and they form pairs so adenine pairs with thymine, and guanine pairs with cytosine. ![]() They string into a linear chain to form a molecule, and these, uh, there are two strands that are twisted around each other to form a double helix. So you can think of those as four letters. They encode information, as sequences of nucleotides, and in the DNA it’s adenine, thymine, guanine and cytosine. Structure of DNA and Genetic Material Īnd we know exactly what it is. And this is actually an extremely important point: Genes are solid particles that are transmitted from parent to offspring. We have known that since 1945, and we’ve known its structure since 1953. So the genetic material is deoxyribose nucleic acid. Some of this may already be very familiar to you. And please speed me up or slow me down, as you wish, and don’t hesitate to interrupt. So now I’m going to run through, as much as I can, genetics, in the next forty minutes. I do that at the beginning just to point out that there are interesting issues here, and that they are things that touch our daily lives. So that, just on the face of it, would indicate that maybe John ought to be worried.īut in fact just exactly how worried should he be just based on genetics, not based on behavior or rumors or anything like that? Well we’ll come back to that. And John comes from an island where one percent of the people have blue eyes. In fact, if you want to write a paper on the evolution of eye color and the genetics of eye color, there’s a lot out there. The actual situation is a bit more complex. Well, we can assume that brown eyes are dominant to blue, which roughly speaking is correct. Should John be worried? John’s got brown eyes, the baby’s got blue eyes, should John be worried? Okay? All of the other men whom Jill knows have blue eyes. Jill and John are going to have a baby, and Jill’s got blue eyes and John’s got brown eyes. So I want to start by posing you a problem. You can download pictures from the Web that just look fantastic. Isn’t that a great shot of the baby? I mean, the Web is so great. Professor Stephen Stearns: Okay, I’m going to start with an example. Transport proteins that are involved in this type of transport are referred to as exchangers or antiporters.Principles of Evolution, Ecology and Behavior E&EB 122 - Lecture 2 - Basic Transmission Genetics ![]() In exchange, the driving ion and the driven ion/molecule are transported across the biological membrane in opposite directions.Īn example is the Na +/Ca 2+ exchanger (NCX), which couples the movement of 3 Na + ions into the cell down its electrochemical gradient to the movement of 1 Ca 2+ ion out of the cell against its electrochemical gradient.Įxchange is also commonly referred to as antiport. The ion/molecule being transported against a chemical or electrochemical gradient is referred to as the driven ion/molecule. The ion moving down its electrochemical gradient is referred to as the driving ion. Definition:A type of secondary active transport across a biological membrane in which a transport protein couples the movement of an ion (usually Na + or H +) down its electrochemical gradient to the movement of another ion or molecule against a concentration or electrochemical gradient. ![]()
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