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Cell Biology

Learn the toughest concepts covered in Cell Biology with step-by-step video tutorials and practice problems by world-class tutors

17. Meiosis and Sexual Reproduction

Basics of Meiotic Genetics


Meiotic Genetics

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Hi in this video we're gonna be talking about the basics of biotic genetics. So the first thing we're gonna do is just review sexual reproduction and a sexual reproduction. Now I know you've known you've talked about this a ton of times in the past but we're just gonna review it real fast. So sexual reproduction involves mixing D. N. A. From two individuals. And this has the benefit of being producing genetically distinct offspring. So offspring that aren't identical. And so um it allows for genetic diversity. And this is really awesome because you can reshuffle genes or mutations that provide competitive advantages. So it makes the offspring stronger in some way. It also has the ability to select out mutated genes. So certain mutations would maybe make individuals less likely to reproduce either by biological mechanisms or social cues. And whatever this because these mutants aren't going to be passed on to offspring and so they'll die out of the population. So it's a super beneficial. Now the other term is a sexual reproduction which is supposed to be highlighted and not cross through. And a sexual reproduction produces offspring that's identical to the parents and to the siblings. And so um this is great in some ways, especially if you live in one environment and that environment never changes. But it's unfortunate because the offspring aren't as adaptable. So that means if something comes into that environment and the organism now needs to change, it has no way to do that because all of its offspring are completely identical. So here's a sexual versus sexual reproduction. So you already have some organisms here. So this is the a sexual form you can see that the offspring is genetically identical to the parent. Whereas in sexual reproduction you get a mixture of these different colors which are gonna just say our genes because it comes from two parents or two individuals mix their genetic information to form the offspring. So um let's talk more about sexual reproduction because that's exactly what mitosis is and that's what this entire chapter is about. And so sexual reproduction involves dividing and segregating out information from both of the parents. So we call these um kind of sex cells. We call them germ cells and they only need to contain 11 set of chromosomes. I'm so in humans we call them egg and sperm. Um and so they only contain like half the genetic information essentially. And so the rest of the cells of the body that aren't used for reproduction are called somatic cells. Um And they actually need both sets of the chromosomes. So we say that half sales this is that term. I just use that, I'm sure you heard of we say that germ cells are half Lloyd cells and they contain half the genetic information. So they only contain one copy of every gene. But we know that in our cells we actually need all of our somatic cells have two copies of gene, one from each of our parents. And so half Lloyd cells only contain um one copy of every gene. And so when the two come together so when the sperm and the egg come together, these two half Lloyd cells form what we call a deployed cell which contains two copies of every gene or like one set of genetic info. So deployed sales, they contain the full amount of genetic information, two copies of every gene, exactly what I just said. And so we refer to these two copies are the two sets of chromosomes as um homologous chromosomes. So they are chromosome pair so one chromosome from the other one chromosome from the father. But they have the exact same genes. There is an exception to this which I'm sure you're all familiar with. And that's our sex chromosomes because these are X and Y. And the X and Y chromosomes are technically a pair. They're the sex chromosomes but the X. And the Y. Have different genetic information on them. So this is kind of what this looks like. So we started out with our half Lloyd which has one red gene and one black or one black chromosome, one red chromosome and fertilized. So the two come together they form a deployed which has two black chromosomes to read chromosomes and then this king undergo mitosis to turn back into a half Lloyd sell or produce offspring. Rather that's a half Lloyd cell. So with that let's now turn the page

Germ cells are diploid.


Fill in the blanks. Haploid cells have _______ copy of genetic material, while diploid cells have ____ copies of genetic material.