Unit 5: Topic 2 - Meiosis and Genetic Diversity

Question 1

Explain the concept of independent assortment in meiosis I.

Answer 1

In metaphase I, the homologous pairs of chromosomes line up in the center randomly. This means that the paternal version of the chromosome can be on the left or on the right (same as the maternal version). This results in each of the two daughter cells randomly receiving the maternal or paternal version of the homologous chromosomes, so each of the 4 daughter cells of meiosis will be made of both maternal and paternal chromosomes.

Question 2

Explain the process of crossing over in prophase I.

Answer 2

In prophase I, homologous chromosomes pair up and exchange portions of genetic material. This process is known as crossing over, and this helps increase genetic variation in the resulting gametes by creating new combinations of genes.

A diagram to help visualize this

Question 3

List and explain the major aspects of meiosis and fertilization that increase genetic variety in offspring.

Answer 3

The three major factors that increase genetic variety are crossing over, independent assortment, and random fertilization.
Crossing over: The process of crossing over in prophase I increases genetic variety by creating new combinations of alleles (alleles are essentially different versions of a gene; this will be explained later).
Independent Assortment: Independent assortment in both metaphase I and metaphase II results in increased genetic variety. Independent assortment in metaphase I refers to the fact that whether the cell (refers to the 2 daughter cells at the end of meiosis I) will receive the maternal or paternal version of the chromosome is random. Independent assortment in metaphase II refers to the fact that which sister chromatid the daughter cell will recieve is random (the two sister chromatids were initially identical, but they are different by metaphase II due to crossing over).
Random fertilization: Random fertilization means that which sperm will fertilize the egg is random. This increases genetic variety since different sperm are not genetically identical.