Thursday, February 4, 2010

1. MEIOSIS: NONDISJUCTION


Click here to watch an animation non disjunction during meiosis.

Questions:
1. In this animation, at what stage of meiosis does non disjunction occur?
2. What is the result of non disjunction?

9 comments:

  1. 1) The nondisjunction happens in anaphase !

    2) Because of nondisjunction all of the gametes have either one less or one more chromosomes. Therefore whichever one of the sperm gametes fertilizes the egg there will be a "malfunction".

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  2. 1. In this animation, at what stage of meiosis does non disjunction occur?
    Anaphase 1

    2. What is the result of this non disjunction?
    At the end, 2 of the cells only have 1 chromosome each.

    -Leina Sheehy 7D

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  3. Okay, in a plant cell, where do the spindle fibers come from? There are no centrioles in a plant cell!


    - Rae Finio 7D

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  4. Rae, good observation. Scientists haven't yet identified the origin of the spindle fibers in plant cells.

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  5. Domonique Rose
    -non didjunction occurred in Meiosis 1
    -the resultsare 1 cell will have too many chromosomes, and the embryo may develope down-syndrome

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  6. First of all, what would be the difference between the chromosomal aberrations in which non-disjunction occurs in anaphase I or II?

    Second of all, here are the answers to the questions:
    1. In this animation, at what stage of meiosis does non disjunction occur?
    In this animation, non disjunction occurs in anaphase I.
    2. What is the result of non disjunction?
    The result of non disjunction is each gamete that is produced has one extra or one less chromosome.

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  7. Nina, the picture on this post shows how the gametes resulting from meiosis differ if non disjunction occurs in meiosis 1 or meiosis 2.
    How many gametes show an irregular number of chromosomes if non-disjunction occurs in anaphase 1?
    How many gametes show an irregular number of chromosomes if non-disjunction occurs in anaphase 2?

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  8. No, I know, I was just asking about the defects in the human but I now realize it's just based on chance on which sperm (with one extra chromosome, one less chromosome, or normal) or egg (with one extra chromosome, one less chromosome, or normal) is fertilized. Thanks!

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  9. 1) In this video, non-disjunction happens in Anaphase I.
    2) Non-disjunction results in some gamtes having too little or too many chromosomes.

    ReplyDelete