DNA question

>>9098426
>When a male produces sperm, is the Y sperm an exact replication of his Y Side of the DNA?
Not exact. All chromosomes during the production of sperm undergo recombination, which produces a lot of the variation in the offspring relative to the parent. Recombination is why you have different traits from your parents essentially. But the Y chromosome doesn't undergo recombination, it only changes through accumulated mutation. Which is why we use it to investigate genetic lineages.

>I assumed you get one side of your DNA from your mother, and one side from your father.
Yes, half and half. Some of your sperm have X chromosome, some have the Y chromosome. If the Y sperm fertilizes the female's egg (which always has an X chromosome), the offspring is XY, therefore male. But the rest of the genome is very similar functionally between the mother and the father. It's the sex chromosomes that differ greatly.

All the germ cells (sperm or egg) derive from normal cells in your body, so called somatic cells. But sperm and eggs only have half the DNA normally present in your body's cells, which happens through meiosis. So when they fuse with the other germ cell, be it sperm or egg, they obtain the other half of the DNA and have a normal quantity of DNA again.

>>9098426
>When a male produces sperm, is the Y sperm an exact replication of his Y Side of the DNA?
No, the human Y chromosome is highly susceptible to mutations as it is passed exclusively through sperm

>how does your body pick millions of pieces from your DNA from your mother and father and place them in the correct order in your sperm or egg cells? It can just pick the pieces and assemble brand new DNA?
The chromosomal DNA is replicated and then packed into chromosomes. Then segments are randomly crossed over between each chromosome in a pair. Then the germ cells are divided once more resulting in one pair of chromosomes (randomly from mother/father) in each of the four resulting sex cells. Look up "meiosis" for more information.

>>9098448
>>9098451
Okay so basically when a male produces a sperm cell, the DNA in that sperm cell is essentially genetic material grabbed from both the X and Y side, the tagged with a Y at the end making it a Y sperm cell? What is the actual process called for copying small bits from the DNA and producing half a dna strand for the sperm/egg cell?

>>9098455
>producing half a dna strand for the sperm/egg cell
No.

Okay, the normal cells in your body have 46 chromosomes in total. But we usually say that a normal cell has 23 pairs of chromosomes instead. That's because 23 chromosomes come from the father, and the other 23 come from the mother. The 22 pairs of chromosomes are very similar in function even though you get them from different parents.But the last pair is the sex chromosome pair, which can be either XY or XX, and again, this pair is given half by the mother (definitely X in the egg) and the father (either X or Y in the sperm, random).

So you get half the DNA in QUANTITY. The body doesn't produce half strands of DNA. It's just that the sperm and eggs have divided in such a way to include only HALF of the chromosomes normally present in your cells, so a sperm or egg has 23 chromosomes, no functionally equivalent pairs.

Regarding sperm cells, as I said, they derive from normal cells. So a normal male cell (XY) divides in such a way that the resulting two cells will have HALF of each chromosome pair. Half of XY. So one sperm has 22 chromosomes plus an X chromosome, and the other sperm has 22 chromosomes plus a Y chromosome. Is that clear enough? I think getting into the specifics of meiosis would confuse you a lot more since it gets a lot more technical.

>>9098475
I get most of what you're saying, I just can't wrap my head around the actual production and compiling of the 23 chromosomes for use in the sperm cell. I just don't understand how the body can produce those 23 chromosomes by gathering information from each parent. In my mind I imagine it like a zipper, unzipping half of the 46 chromosomes then sticking half of it in a sperm cell and sending it off. But I know that it's more like a machine that picks the individual teeth out of the zipper then fits them together like a puzzle to construct the full 23 chromosomes. It just seems way more complicated. Sorry if I'm retarded and completely mis-understanding something

>>9098487
>I just don't understand how the body can produce those 23 chromosomes by gathering information from each parent.
It doesn't produce them by gathering information, a normal cell with 46 chr simply splits into two, and the resulting two cells are the sperm cells, roughly speaking. It's just that during the splitting half goes to the one new cell and half to the other. The original normal cell doesn't exist anymore. No new chromosomes are made during this process.

Forgive me if I'm misunderstanding your confusion.

>>9098496
Okay, see that was my original question though. I'm a male, so my Y side of my DNA should be pretty damn similar to my fathers Y Side, because it's just split down the middle and thrown into the sperm cell. So that means my grand fathers Y side of his DNA should be pretty damn similar to my fathers DNA. Which also means the X side of the DNA I got from my mother would either be from just my moms dad or just my moms mom. So I have a 50% chance of not receiving genetic information from my maternal grandfather?

>>9098525
>Y side
This is important, does "side" include all the 23 chromosomes from your father or are you just referring to the one Y chromosome from your father? The 22 chromosomes from your father are not identical, because of genetic recombination that occurs during the formation of a sperm cell. But the Y chromosome in particular escapes this recombination, therefore is uniquely similar to the one your father got from your grandfather, and so on.

>So I have a 50% chance of not receiving genetic information from my maternal grandfather?
Your analysis is correct, yes.

>>9098451
>No, the human Y chromosome is highly susceptible to mutations as it is passed exclusively through sperm
that's fucking stupid. the y chromosome is just as susceptible as the rest of the haploid genome from the father

>>9098546
>does "side" include all the 23 chromosomes from your father or are you just referring to the one Y chromosome from your father?

I'm referring to the entire 23 chromosomes that I receive from my father. He would've recieve his entire 23 chromosome of the Y side from his father too.

File: crossingover.gif (27KB, 392x400px) Image search: [Google]

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first, you start with two copies of each chromosome. one copy is from the mother, the other is from the father

each copy is duplicated, so you have two copies of each copy, or four total (sister chromatids)

one of the sisters from each pair swaps chromosomal material with one of the sisters from the other pair.

each of those four chromosomes is then packaged into a gamete

this process happens independently for each chromosome. random recombination sites occur in each chromosome, and each quad set of recombined chromosomes is randomly assorted into the final gamete

>>9098607
Okay then yeah, but the non-sex chromosomes passing down from generation to generation change through recombination like I said, so they're not even close to identical from father to son. But the Y chromosome is special in its inhibition of this recombination process, so it stays nigh-identical throughout the generations.

>>9098631
it's more complicated than that in reality. the X and Y chromosomes do segregate together and have a crossover event (necessary for checkpoints and shit in cell division), it's just that most of the chromosomes are so different that nothing is recombined between the two

>>9098598
Wrong.
>Each cellular division provides further opportunity to accumulate base pair mutations. Additionally, sperm are stored in the highly oxidative environment of the testis, which encourages further mutation. These two conditions combined put the Y chromosome at a greater risk of mutation than the rest of the genome.
https://en.wikipedia.org/wiki/Y_chromosome#High_mutation_rate

>>9098666
i know what wikipedia says. it still doesnt pass the smell test. every other chromosome in the genome is also replicated in sperm cells along with the Y chromosome and exposed to the same oxidative conditions. if those two factors were having an effect on mutation rates, they'd be affecting every chromosome equally.

there could be other reasons for a higher mutation rate (i saw one source suggesting there might be mutational hotspots in some regions on Y throwing off the analysis), but those listed environmental factors don't make any sense