Sunday, February 7, 2010

3. MEIOSIS: NON DISJUNCTION

Click here to view an animation on meiosis and the consequences of non disjunction.
Questions:
1. In this animation, when does non-disjunction occur?
2. What fails to separate in this animation?
3. If the the gamete producing cells has 4 chromosomes, how many chromosomes should each gamete contain?

5 comments:

  1. Thanks for posting this after my last comment

    Answers to questions:
    1. In this animation, when does non-disjunction occur?
    In this animation, non-disjunction occurs in anaphase II.
    2. What fails to separate in this animation?
    What fails to separate in this animation is the sister chromatids.
    3. If the gamete producing cells have 4 chromosomes, how many chromosomes should each gamete contain?
    If the gamete producing cells have 4 chromosomes, each gamete should contain 2 chromosomes.

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  2. 1. Anaphase 2
    2. Sister chromatids
    3. 2 because the process is meiosis

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  3. 1) Non-disjunction occurs in anaphase II.
    2) In anaphase II if there is ever non-disjunction the sister chromatids don't separate and that is what happened.
    3) You would get n. If 2n is 4 chromosomes then n would be 2 chromosomes.

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  4. for 2 isn't it the homologous chromosomes

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  5. Waqar, watch the animation.
    You will see how the two pairs of homologous chromosomes (dark blue and light blue, and dark orange and light orange) separate properly during anaphase 1.
    But, during anaphase 2, the dark blue sister chromatids fail to separate to opposite poles of the cell.

    ReplyDelete