Thursday, February 4, 2010

2. MEIOSIS: NON DISJUNCTION

This website shows three animations: 1) crossing over, 2) normal meiotic division in females and fertilization, and 3) non disjunction in Down Syndrome. Also, click on the last box to view an animated power point on meiosis and fertilization.

Questions:
1. What is the difference between spermatogenesis and oogenesis?
2. In humans, how many chromosomes are present in the gametes?
3. In humans, how many chromosomes are present in somatic cells?
4. How do somatic cells divide?

7 comments:

  1. 1) Spermatogenesis happens in males and oogenesis happens in females.

    2) I think that there are 23 chromosomes present in gametes.

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  2. 1. What is the difference between spermatogenesis and oogenesis?

    Spermatogenesis occurs in a man's testes, and oogenesis occurs in a woman's ovaries. Spermatogenesis produces sperm, while oogenesis produces eggs. Spermatogenesis constantly produces millions of sperm, and oogenesis produces one egg each month (4 eggs are produced, but 3 die).
    I think that spermatogenesis begins during puberty and ends almost until death, while oogenesis begins during puberty and ends earlier.
    -Leina Sheehy 7D

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  3. if the baby has 1 Y and 2 Xs, does it matter whether both the sperm and the egg performed nondisjunction?

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  4. -spermatogenesis happens in a male's testes, and makes sperm, where as oogenesis happens in a female's ovaries, and makes eggs.
    -there are 23 chromsomes foun in gametes
    -there are 46 chromosomes in somatic cells
    -somatic cells only go through one division

    DOMONIQUE ROSE

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  5. I think it's interesting that the gamete-producing cells that undergo meiosis to produce gametes also undergo mitosis to reproduce themselves. Also, those gametes (that were produced by meiosis) come together with other gametes to produce a zygote, which in turn divides into many cells by mitosis to create a multi-cellular organism.

    1. What is the difference between spermatogenesis and oogenesis?
    Spermatogenesis is the process in which sperm are produced whereas oogenesis is the process in which eggs are produced. Spermatogenesis and oogenesis occurs in men and women, respectively. While spermatogenesis is always going on in males since puberty, oogenesis occurs from puberty to menopause.
    2. In humans, how many chromosomes are present in the gametes?
    In humans, 23 chromosomes are present in the gametes, classifying them as haploids.
    3. In humans, how many chromosomes are present in somatic cells?
    In humans, 46 chromosomes are present in somatic (body) cells, making them diploids.
    4. How do somatic cells divide?
    Somatic cells divide by mitosis.

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  6. 1. Spermatogenisis happens in men where sperm is produced in the testes. Oogenesis happens in women where eggs are produced in the ovaries.

    2. Gametes are haploid cells which means that they will have half the number of chromosomes as the diploid cell. In humans, 23 is the haploid number.

    3. Somatic cells are diploid cells which means that they have 46 chromosomes.

    4. Somatic cells divide using mitosis.

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  7. Can nondisjunction happen in both Anaphase1 and Anaphase2?

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