Week 8: Meiosis
To-Do Date: Mar 13 at 2:30pmCartoon
In this cartoon, a cell finds a magazine about meiosis under the bed of her child. She is outraged and shocked that a youngster is reading something so racy and sexual. Explain why there is no excuse- any magazine about meiosis is about sex!
Learning Objectives
- By the end of the week you should be able to:
- Explain the difference between sexual and asexual reproduction.
- Explain why meiosis is essential for sexual reproduction.
- Be able to draw, step by step, the process of meiosis.
- Explain why the S–phase of the cell cycle is vital for cell division.
- Distinguish between unique chromosomes and homologous chromosomes.
- Explain how meiosis increases the genetic diversity of the next generation as compared to their parents. (Give two sources.)
- Explain the differences between meiosis and mitosis.
- Explain the differences between Meiosis I and Meiosis II.
- Be able to define the following terms:
| Chromosomes | Meiosis I | Meiosis II |
| centromeres | Prophase I | Prophase II |
| sister chromatids | Anaphase I | Metaphase II |
| homologous chromosomes | Telophase I | Anaphase II |
| genes | synapsis | Telophase II |
| alleles | crossing over | gametes |
| diploid | independent assortment | fertilization |
| haploid |
Study Guide Questions
1. Draw a diploid (2n) cell with 3 pairs of chromosomes (a total of 6 chromosomes) at the end of interphase.
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- Draw that same cell's chromosomes and daughter cells at the end of Meiosis I
- Draw the same cell's chromosomes and daughter cells at the end of Meiosis II
- identify chromosomes by number (ie all the #1 chromosomes should be the same length as each other)
- identify homologous chromosomes by being the same length as each other with centromeres in the same location, but different colors to indicate different alleles.
- include and label : homologous chromosomes, chromatids, crossing over, spindle fibers (only when relevant), the nuclear envelope (only when relevant), the cell membrane
- Note: this is exactly the same as our lab activity, but with one less pair of chromosomes.
2. Compare meiosis and mitosis.
- Make a drawing of a diploid (2n) cell with 3 pairs of chromosomes (a total of 6 chromosomes) at the end of interphase.
- Draw the same cell in each stage of mitosis (prophase, metaphase, anaphase, telophase) and after cytokinesis
- compare each of these stages to the drawing you made above of Meiosis I. In what way are mitosis and meiosis I similar? In what way are they different?
- Compare your drawings of mitosis to that of meiosis II. In what ways are the they similar? Different?
- Compare the end product of mitosis to that of meiosis. In what ways are they similar? Different?
3. What is sexual reproduction and how does meiosis contribute to benefits? Explain this in terms of genetic recombination, independent assortment, crossing over, random fertilization, eggs, sperm, zygotes, genetic variation, stable and unstable environments.