BIOL 1020 Lecture 23: Lecture 23

• School: University of Manitoba
• Department: Biological Sciences
• Course: BIOL 1020
• Professor: Joy Stacey

Document Summary

The behaviour of chromosomes during meiosis and fertilization is responsible for most of the variation that arises in each generation. Creates tremendous amount of variation, which natural selection has selected for. Homologous pairs of chromosomes orient randomly at metaphase i of meiosis l. In independent assortment, each pair of chromosomes sorts maternal and paternal homologues independently of the other pairs into daughter cells. Crossing over produces recombinant chromosomes, which combine genes inherited from each parent. Crossing over begins very early in prophase i, as homologous chromosomes pairs up gene by gene. In crossing over, homologous portions of two nonsister chromatids trade places. Crossing over contributes to genetic variation by combining dna from two parents into a single chromosome. Hair color and eye color are genes that are found very close together on a chromosome. There are locations on chromosomes where they readily break and re-attach- the chiasma.