Download the attached file. Activity 2 can be done as an electronic file in Word and follow the directions in the document. Please answer all questions in file form. No handwritten answers please.
Pre-Lab Assignment Lab Module 8: Mitosis & Meiosis
Complete and submit as a file upload for your pre-lab assignment.
Activity 1: Suppose that there was a mistake in meiosis so a human egg received two copies of chromosome Suppose that this egg was fertilized by a normal sperm.
How many copies of chromosome 21 would be in the resulting zygote? ___
How many copies of chromosome 21 would be in each cell in the embryo that developed from this zygote? ___
When cells have three copies of a chromosome, the extra copies of the genes on this chromosome result in abnormal cell function and abnormal embryonic development. To understand why, remember that each chromosome has genes with the instructions to make specific types of proteins; an extra copy of the chromosome can result in too many copies of these specific proteins.
Some babies are born with an extra copy of chromosome 21 in each cell. This results in Down syndrome with multiple abnormalities, including mental retardation, a broad flat face, a big tongue, short height, and often heart defects.
| This figure shows a karyotype for a normal boy. A karyotype is a photograph of a magnified view of the chromosomes from a human cell, with pairs of homologous chromosomes arranged next to each other and numbered. Each chromosome has a pair of sister chromatids attached at a centromere. 3. A karyotype is prepared from a cell that is
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How do you know?
4a. Label the sister chromatids in chromosome 3 in the karyotype.
4b. Draw an extra chromosome 21 to show the karyotype of a boy with Down syndrome.
If each cell in an embryo has an extra copy of one of the chromosomes in the top row of the karyotype, the resulting abnormalities are so severe that the embryo always dies. In contrast, an extra copy of chromosome 21 results in less severe abnormalities so the embryo can often survive to be born as a baby with Down syndrome.
5. What do you think is the reason why an extra copy of chromosome 1, 2, 3, 4 or 5 results in more severe abnormalities than an extra copy of chromosome 21?
6. What is non-disjunction?
Activity 2: Drag the images into the proper order for meiosis (Hint: you have to do this while it’s an electronic document). If you choose to print, then cut the images out and paste on another sheet in the proper order. AFTER you drag or print/cut/paste, label each of the phases correctly.
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| 5. | 6. | 7.
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Activity 3:Fill in the table to compare & contrast mitosis and meiosis in humans.
| Mitosis | Meiosis | |
| # of chromosomes in parent cell | ||
| Used for repair, reproduction and/or growth? | ||
| Type of cells produced? | ||
| Number of nuclear and cell divisions? | ||
| Crossing over? Independent Assortment? | ||
| Number of daughter cells? | ||
| # of chromosomes in daughter cells? | ||
| Haploid or diploid daughter cells? |
