Question

intro. to meiosis webquest
name: payton dorsey
task 1: introduction to meiosis
click below to watch the “meiosis” video by the amoeba sisters. as you watch, answer the following questions.
click here

1. what does the process of meiosis contribute to?
2. what type of cells does meiosis produce?
3. how many chromosomes does a human sperm cell or egg cell contain?
4. why is meiosis a “reduction division”?
5. which phase must take place before meiosis starts?
6. how many times is “pmat” carried out in meiosis?
7. describe what happens during prophase.
8. what happens during crossing over?
9. where are the chromosomes during metaphase i?
10. what happens during anaphase i?
11. how many cells exist after meiosis i?
12. what is pulled away by the spindle fibers during anaphase ii?
13. what happens during telophase ii?

Explanation:

1. Meiosis contributes to genetic diversity through processes like crossing - over and independent assortment. It is also essential for sexual reproduction as it produces gametes.
2. Meiosis produces gametes, which are sex cells. In humans, these are sperm cells in males and egg cells in females.
3. A human sperm cell or egg cell contains 23 chromosomes. These are haploid cells.
4. Meiosis is a "reduction division" because the parent cell is diploid (has two sets of chromosomes) and the resulting gametes are haploid (have one set of chromosomes), reducing the chromosome number by half.
5. Interphase must take place before meiosis starts. During interphase, the cell grows, replicates its DNA, and prepares for cell division.
6. "PMAT" (Prophase, Metaphase, Anaphase, Telophase) is carried out twice in meiosis, once in Meiosis I and once in Meiosis II.
7. During prophase I of meiosis, homologous chromosomes pair up (synapsis) and crossing - over occurs, where segments of non - sister chromatids are exchanged. In prophase II, the nuclear envelope breaks down and spindle fibers form.
8. During crossing over, segments of non - sister chromatids of homologous chromosomes exchange genetic material, increasing genetic diversity.
9. During metaphase I, the homologous chromosome pairs line up along the equator (metaphase plate) of the cell.
10. During anaphase I, the homologous chromosomes are pulled apart to opposite poles of the cell by the spindle fibers.
11. After Meiosis I, two cells exist. These cells are haploid but each chromosome still consists of two sister chromatids.
12. During anaphase II, the sister chromatids are pulled apart by the spindle fibers and move to opposite poles of the cell.
13. During telophase II, the nuclear envelope reforms around the separated chromosomes, the spindle fibers break down, and cytokinesis occurs, resulting in four haploid daughter cells.

Answer:

1. Genetic diversity and sexual reproduction.
2. Gametes (sex cells).
3. 23 chromosomes.
4. Reduces chromosome number from diploid to haploid.
5. Interphase.
6. Twice.
7. In prophase I: Homologous chromosomes pair up and crossing - over occurs. In prophase II: Nuclear envelope breaks down and spindle fibers form.
8. Segments of non - sister chromatids exchange genetic material.
9. Homologous chromosome pairs line up along the metaphase plate.
10. Homologous chromosomes are pulled to opposite poles.
11. Two cells.
12. Sister chromatids.
13. Nuclear envelope reforms, spindle fibers break down, and cytokinesis occurs, resulting in four haploid daughter cells.