Question

Exemplify sources of genetic variation in sexually reproducing organisms including crossing over, random assortment of chromosomes, gene mutation, nondisjunction, and fertilization.

⦁ What is crossing over? How does this cause variation?

Answer 1

Crossing over is a process that occurs during meiosis and involves the exchange of genetic material between homologous chromosomes. It leads to the creation of genetic variation by producing new combinations of alleles on each chromosome.

Step-by-step explanation:

Crossing over is a process that occurs during meiosis, specifically during prophase I. It involves the exchange of genetic material between homologous chromosomes. Crossing over leads to the creation of genetic variation by producing new combinations of alleles on each chromosome.

During crossing over, homologous chromosomes pair up and form structures called tetrads. Within each tetrad, non-sister chromatids (one from the mother and one from the father) break at the same locations and exchange segments of DNA. This exchange results in the swapping of genetic information between the two chromosomes.

For example, let's say there are two homologous chromosomes, one from the mother and one from the father. Through crossing over, a segment of DNA from the mother's chromosome can be swapped with a segment of DNA from the father's chromosome. This creates two new chromosomes, one with a combination of the mother's and father's genetic material and another with a combination of the father's and mother's genetic material. These new combinations of alleles can lead to the expression of different traits in offspring.

Overall, crossing over promotes genetic diversity within a population by generating new combinations of alleles on chromosomes.