How DNA stores genetic information

37:34got kind of a more complete picture of how genes work and how Mendle's laws come from genes. So I just want to go over all of that. Okay, so first we know now from, you know, all of the work is DNA stores the data of these alals and genes. And what an alle really is is one version of the ATGC sequence. Okay, the different alil will be a different version of that ATGC sequence, right? and the two alals are different in only a few base pairs because that's going to code for a different protein and that protein is going to make the different trait. >> For folks who might not know, when you say ATCG sequence, can you clarify? >> Yeah. Yeah. Yeah. Yeah. Good point. Um the ATCGs are the nucleotides that make

38:14up DNA. So DNA is a molecule that's kind of a twisted ladder and the rungs of the ladder come in four different types A, T, G, and C. The sequence of those letters in that ladder tell you what kind of protein to make. >> Okay? >> So, it's like they're rungs on the ladder. They can be in different order. And so, you can do different things based on the order that they're in. And each chromosome comes in with a different rungs on the latter order from each of the parents in this context. >> Yes. Exactly. And when we say that there are two alals, what we really mean is there's two distinct sequences of ATGC's, right, that will code for the protein. And though and that DNA is stored in the chromosome. So when we see the chromosome like the two strands,

38:55each strand is a giant molecule, a single molecule of DNA that if you were to unravel would be like this big literally like that fits inside every single one of our cells. But it's like it's like several inches long. >> That's so >> right a single molecule of just ATGC strung together, right? And it's wrapped around a bunch of stuff to create the chromosomes. So that's what a chromosome is. All right, now we know what a chromosome is. Now each chromosome as we said has two chromatids. Those are the two different sequences of DNA and each alil is located on the different chromatids. So now when we look at the laws of independent assortment and things like that and how to create gameamtes well during meiosis the two chromatids they replicate and then they

39:37physically separate into different cells. So the sperm cells all get half one chromatid each. And that's now making sense right with the whole punet squares and all that stuff. How's that working? Well, when the egg and the sperm come together, you get half and half to create a hole. Right. Right. So, so now that that's making sense. Now, the independent assortment works. The whole correlated genes also works because if you're on the same chromatid, then you're going to get the same package. And then finally, how does the dominant and um recessive work, right? Well, a lot of times the dominant version just codes for the protein that works and the recessive version codes for the protein that doesn't work. So if you get two dominance, you just get

40:18maybe a little bit more of the protein. There can be some gene regulation stuff to like downplay one of the chromatids so that I don't like have too much of the same protein. There's actually stuff that goes on there which is very interesting. But if I have like the hetererozygous meaning one functional type and one dysfunctional type, I still have working copy. So I can create that gene. But if I have two dysfunctional types, then I've got no way to create the gene. Eye color is a very good example of this. the um OCA2 alil combinations. So um there's a there's a gene for mel melanosome melanosome