Answer to Question #306120 in Cell Biology for Roz

Question

Describe the process of ‘crossing over’ detailing at what stage of the cell cycle it occurs. What effect does crossing-over process have on linked genes with respect to the relative distance on the chromosome? How can we calculate the distance of two linked genes? (150 words)

Answer 1

During meiosis I in prophase I, crossing over takes place and is the process where two homologous non-sister chromatids pair up with each other and exchange different segments of genetic material to form two recombinant chromosome sister chromatids.

Crossing over can put new alleles together in combination on the same chromosome, causing them to go into the same gamete. When genes are far apart, crossing over happens often enough that all types of gametes are produced with 25% frequency.

The linkage distance is calculated by dividing the total number of recombinant gametes into the total number of gametes.