Make a Life to Save a Life, Hour 2

Challenge 1:

Sexually reproducing organisms undergo meiosis to produce sex cells (sperm and eggs). Imagine that you were to observe the following chromosomes in the nucleus of a sperm cell:

sperm_cell

What would you expect the chromosomes to look like in the nucleus of a skin cell from that same organism?

Challenge 2:

In animals, skin cells divide again and again to produce many new skin cells. Imagine that an original skin cell contained all of the chromosomes shown in this diagram:

skin_cell

What would you expect the chromosomes to look like in the nucleus of an egg cell from that same organism?
(For each pair of homologous chromosomes, one homologue is colored gray and the other black.)


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32 Responses to Make a Life to Save a Life, Hour 2

  1. Walker J, Daniel S says:

    Challenge 2

    • Walker J, Daniel S says:

      We would expect there two be half as many chromosomes because the egg cell is a haploid cell.

      • Mr. Mohn says:

        You are correct that there should be “half as many chromosomes,” but your picture actually still shows four chromosomes (they are just no longer duplicated). This would be what a skin cell after mitosis would look like.

  2. Jared C., Carter G. says:

    In the egg cell, the amount of chromosomes would be half as much.

  3. Kylie M., Jason K. says:

    Each of the chromosomes would be matched with a corresponding chromosome from the other parent.

    • Alessander R. Megan S. says:

      That is what we got as well but we didn’t think about the matching.

    • Mr. Mohn says:

      The way you have drawn this indicates that there are three duplicated chromosomes. If you wanted to represent the idea that the chromosomes are matched in pairs, there should be six total chromosomes.

  4. Alessander R. Megan S. says:

    Challenge 1
    They would be duplicated.

  5. Eden K and Stacie W says:

    There will be a total of six pairs of chromosomes, as the skin cell is a diploid cell.

  6. Sirat G Sunny H says:

    The chromosomes would just have their sister chromatid.

    • Mr. Mohn says:

      This is only three chromosomes. They are duplicated, but they are still individual chromosomes. A skin cell from this organism would be diploid. That means it would have homologous pairs of chromosomes, for an overall total of six.

  7. Parker J. and Lauren F. says:

    There are a total of 6 pairs of chromosomes in the skin cell. The single strands are bonded together, then duplicated.

    • Anita S. and Cole W. says:

      There are not going to be 6 pairs in the skin cell because the chromosomes do not duplicate when becoming haploid. Rather they just join with another sister chromatid. This is why there should be only three chromosomes in the end result and not six.

    • Mr. Mohn says:

      Parker and Lauren- your drawing is correct. However, your description of “six pairs” is not what your drawing illustrates. Your drawing shows a skin cell with three pairs of homologous chromosomes.

  8. Anita S. and Cole W. says:

    We completed challenge 1 ,and we expected that the chromosomes would be duplicated and be made into sister chromatids. We knew this because the haploid sperm cell’s chromosomes would be changed into diploid chromosomes in a skin cell.

    • Mr. Mohn says:

      You are correct that your picture shows duplicated chromosomes. However, your drawing only shows one chromosome of each type. A diploid cell has two chromosomes of each type (“homologous pairs”).

  9. Erin B, Ronak L. says:

    The chromatids receive their homologous pair.

  10. Erin B, Ronak L. says:

    forgot picture

    • Mr. Mohn says:

      Your drawing only shows one chromosome of each type. A diploid cell has two chromosomes of each type (“homologous pairs”). There should be six total chromosomes in the nucleus of a skin cell from this organism.

  11. Alex T., Eric C. says:

    We completed the first challenge, and we asserted that there are 6 pairs in a healthy body cell, two of each sort.

  12. Vandita G., Will B. says:

    We chose to complete challenge 1. There would be a pair of homologous chromosomes in the nucleus of a skin cell from the same organisms. These chromosomes would not be connected at the centromere because they are homologous.

    • Mr. Mohn says:

      Your description is correct. There should be pairs of chromosomes in the nucleus of a skin cell for a total of six chromosomes overall. These “homologues” would not be connected at the centromere.

      However, your drawing shows the pieces of genetic material overlapping in a manner that seems to indicate that they ARE connected at the centromere. Was this intentional or a mistake?

  13. Gabby G., Brian E. says:

    Each chromosome is duplicated and becomes part of a haploid cell.

  14. Adam C.. Elizabeth S. says:

    We completed challenge number 2 and our results are one chromosome from each pair.

    • Mr. Mohn says:

      Both cells in your drawing show a nucleus with four chromosomes. On the left, they are duplicated chromosomes consisting of two sister chromatids. On the right, they are not duplicated.

      The difference between is diploid skin cell and a haploid egg cell is that the egg cell should have HALF the number of chromosomes compared to the original (only one chromosome from each pair). In this case, your cell on the right should only have two chromosomes, not four.

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