Why is crossing over important in heredity | Homework Helpers

Cellular reproduction in Eukaryotes involves either mitosis or, in the case of sex cells, meiosis. Mitosis involves the reproduction of a cell into two identical daughter cells. Meiosis, however, is a reduction division where a parental diploid cell produces four haploid gametes. Upon fusion, two haploid gametes (in humans the sperm and the egg) will result in one diploid zygote. In this activity you will track chromosomes through meiosis using colored beads.

Questions:

1. Why is crossing over important in heredity?

2. Provide two ways that meiosis I and meiosis II are different.

3. a. In 0the lab, how many chromosomes were present in each cell when meiosis I started?

b. How many chromosomes were present in each daughter cell at the end of meiosis II?

4. If humans have 46 chromosomes in each of their body cells, determine how many chromosomes you would expect to find in the following :

Sperm:

Egg:

Daughter cell from mitosis:

Daughter cell from meiosis II:

5. Why is it necessary to reduce the chromosome number of gametes, but not of other cells of an organism?