Meiosis (MOD4) Watch

Venom123
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#1
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Basically, i've just read through this section

I understand the geist of two stages of meiosis

just want to get this straight, i'm guessing as the gametes are within' the sex cell of each parent, so meiosis occurs in both sex before 'sexual intercourse' okay...

But what is the purpose of crossing over then in the chiasma:| in prophase I...

explain... explain
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whitepearlbaby
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What do you mean meiosis occurs in both sex? Do you mean mitosis?

And the crossing-over is needed for the recombination of the DNA Otherwise you'd look exactly like one of your parents I think
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spank_
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There's no purpose for the crossing over. As far as i know it just happens by chance. however the crossing over produces new combinations of alleles which can increase variation within a species
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jdfan
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(Original post by Venom123)
Basically, i've just read through this section

I understand the geist of two stages of meiosis

just want to get this straight, i'm guessing as the gametes are within' the sex cell of each parent, so meiosis occurs in both sex before 'sexual intercourse' okay...

But what is the purpose of crossing over then in the chiasma:| in prophase I...

explain... explain
Yes - Meiosis occurs in both sexes before intercourse in order to create the gametes (sex cells). Fertilisation of the gametes occurs when the sperm and the egg cell join.

Crossing over occurs during Meiosis and it involves the homologous chromosomes exchanging sections of their chromatids, creating new allele combinations. This occurs randomly but is one of the causes of genetic variation and is therefore why we all look differently from one another.
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poossum
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It is the increased genetic diversity that is its purpose- less chance of inbreeding, greater immunity to a species wide disease etc.
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Venom123
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(Original post by poossum)
It is the increased genetic diversity that is its purpose- less chance of inbreeding, greater immunity to a species wide disease etc.
Cheers bud all I wanted

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