AP BIOLOGY

Detailed explanation-1: -Definition. Crossing over, as related to genetics and genomics, refers to the exchange of DNA between paired homologous chromosomes (one from each parent) that occurs during the development of egg and sperm cells (meiosis).

Detailed explanation-2: -Crossing over is an enzyme-mediated process, where the exchange of genetic material between non-sister chromatids of homologous chromosomes takes place. It occurs at the pachytene stage of prophase I of meiosis.

Detailed explanation-3: -Meiosis also produces genetic variation by way of the process of recombination. Later, this variation is increased even further when two gametes unite during fertilization, thereby creating offspring with unique combinations of DNA.

Detailed explanation-4: -Meiosis, from the Greek word meioun, meaning “to make small, ” refers to the specialized process by which germ cells divide to produce gametes. Because the chromosome number of a species remains the same from one generation to the next, the chromosome number of germ cells must be reduced by half during meiosis.