Need help understanding meiosis

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WiseIdiot
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Need help understanding meiosis

Post by WiseIdiot » Mon Oct 20, 2008 4:34 am

By the end of Meiosis II, an organism has formed 4 haploid cells, which develop into gametes. The chromosomes belonging to these haploid cells were once homologous. When the gametes from the partner come to fertilize these cells, a zygote forms. Now considering that there are four cells, will not there be four zygotes? Does this mean that the offspring will have all of these four zygotes or just one of them?

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MichaelXY
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Re: Need help understanding meiosis

Post by MichaelXY » Mon Oct 20, 2008 6:08 am

WiseIdiot wrote:By the end of Meiosis II, an organism has formed 4 haploid cells, which develop into gametes. The chromosomes belonging to these haploid cells were once homologous. When the gametes from the partner come to fertilize these cells, a zygote forms. Now considering that there are four cells, will not there be four zygotes? Does this mean that the offspring will have all of these four zygotes or just one of them?


I think I see your confusion. Yes Meiosis makes four cells, but do not confuse this with fertilization. Meiosis creates germ cells like sperm and egg, so after Meiosis each germ cell has different combos of mom and dad genes. Now these germ cells are used in fertilization (as in sex) and only one germ cell will be used from the male and one from female. This creates a single zygote which undergoes mitosis.

Maybe someone has a better explanation.

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MrMistery
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Post by MrMistery » Mon Oct 20, 2008 3:29 pm

Each cell that undergoes meiosis produces four gametes. But think of it like this: millions of cells will undergo meiosis constantly in your body. Every time you have sex, out of millions of sperm cells only one will fertilize an egg cell, resulting in one zygote. Out of your initial four cells, only one actually participates in fertilization, resulting in a zygote.
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