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daughter cell of meiosis I

Discussion in 'MCAT Study Question Q&A' started by m25, 09.29.14.

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  1. m25

    m25

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    Why is the daughter cell of meiosis I considered to be a haploid rather than a diploid? Like, how are haploid and diploid defined in terms of the MCAT?

    And since the haploid daughter cell of meiosis I looks like X and the diploid cell in mitosis also looks like X , then does that mean when we are presented with a diagram that looks like X on the MCAT, we cannot tell if it is 2N or N without first knowing if the cell is going through mitosis or meiosis, correct?

    And in terms of the MCAT, do human cells ever have 4N in it's life cycle?
     
    Last edited: 09.30.14
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  3. Hadi7183

    Hadi7183 2+ Year Member

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    What you see as "X" after meiosis I is a pair of sister chromatids and not a pair of homologues. Only the latter corresponds to a diploid cell, because two DNA strains are not identical. A pair of sister chromatids, even though they have gone through recombination and slightly changed, are technically considered to be same even if you physically see two strains. Having a pair of sister chromatids doesn't mean diploidy.

    And I guess prior to meiosis I, germ cells briefly exist as 4N state.
     
    kraskadva likes this.
  4. AwayFromReality

    AwayFromReality 2+ Year Member

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    The whole replication process, the way I understand it, is this:

    Normally humans have 46 chromosomes in 23 homologous pairs (Diploid)
    Replication increases to 96 chromosomes in 46 homologous pairs(Diploid). The 46 pairs that you have are made up of two X joined together, forming a tetrad XX.
    Meiosis I goes through and you now have 46 chromosomes in the form of X (which is known as a Diad). You are now Haploid.
    Meiosis II proceeds like mitosis, giving each germ cell 23 chromosomes (Still haploid). Each cell has a chromatid from the diad so X breaks up into | and |.

    Therefore, for the purposes of the MCAT, diploid means that there are homologous pairs. If you don't have homologous pairs you are haploid.

    PS: This is what I understood from my studying, if I am wrong someone please explain it to me
     

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