5.2 Meiosis and Genetic Diversity

Heritable information provides for continuity of life. Explain how the process of meiosis generates genetic diversity. Separation of the homologous chromosomes in meiosis 1 ensures that each gamete receives a haploid (1n) set of chromosomes that comprises both maternal and paternal chromosomes. During meiosis I, homologous chromatids exchange genetic material via a process called "crossing over" (recombination), which increases genetic diversity among the resultant gametes. Sexual reproduction in eukaryotes involving gamete formation-- including crossing over, the random assortment of chromosomes during meiosis, and subsequent fertilization of gametes -- serves to increase variation.

prophase I

pairing of homologous chromosomes → tetrads, aka synapsis, causing genetic recombination/crossing over

• leads to new genetic combinants and recombinants

linked genes

genes that are close together tend to be inherited together

• frequency of recombination can be used to estimate distance between genes

independent assortment

random orientation of tetrads allows daughter cells to receive a random combination of chromosomes, possibilities increase with more chromosomes

random fertilization and mutation

also increases genetic diversity