Linkage, Recombination, and Crossing Over

Question 1

Recombination

Answer 1

Exchange between homologous chromosomes

Occurs during prophase I of meiosis

Homologous chromosomes form tetrad

Occurs at chiasma (physical junction between homologous chromatids)

The closer genes are to each other on the chromosome, the likelier they are to crossover together, decreasing the likelihood of a recombinant gamete (because both genes cross over)

Question 2

Recombination Frequency and Genetic Map Distance

Answer 2

Genes could be over 100 map units apart, but that doesn’t mean recombination is over 100%

After 50%, there is so much crossover occurring that the genes act like they are on separate chromosomes