5.2: Meiosis and Genetic diversity

Question 1

When do homologous chromosomes separate during meiosis?

Answer 1

During anaphase I, homologous chromosomes separate.

Question 2

How do homologous chromosomes separate during anaphase?

Answer 2

Each spindle fiber is is attached to a one chromosome in each homologous pair, so during anaphase I, they are pulled apart to opposite poles.

Question 3

How do daughter cells receive both maternal and paternal chromosomes?

Answer 3

The sex cell in the mother contains the same genes from each of its parents. As meiosis occurs, crossing over between the two happen and the end result is four haploid cells. The same happens with the father. Then, two of the four haploid cells would fuse together during fertilization, leading to further genetic variation.

Question 4

What process occurs during meiosis I that causes daughter cells to be haploid?

Answer 4

During meiosis, the cell goes through each phase twice, resulting in half of the chromosomes in each cell (haploid).

Question 5

What is crossing over?

Answer 5

Crossing over occurs during prophase I when nonsister chromatids exchange genetic material, forming recombinant chromosomes.

Question 6

How does crossing over increase genetic diversity?

Answer 6

The double homologous chromosomes exchange some sections of DNA and then split into different cells soon after. This means that the cells would have different DNA than each other, leading to more genetic diversity.

Question 7

What is independent assortment? How does it increase genetic diversity?

Answer 7

Independent assortment means that two traits are not on the same chromosome as each other, so the probability that both are in the offspring becomes less. This means that the cross would lead to YR, Yr, yR, and yr for each parent. This creates 16 options as opposed to sorting dependently, which would be YR and yr for each parent.

Question 8

What is random fertilization? How does it increase genetic diversity?

Answer 8

Random fertilization means that the father produces four haploid sex cells and the mother also produces four haploid sex cells. Only two will fuse together. This means that there are 16 combinations of offspring (more genetic variation).