03-121 | Linkage and Recombination (30)

what is crossing over

the exchange of genes between homologous chromosomes, resulting in a mixture of parental characteristics in offspring.

what do homologs interact via

synapse/chiasma

when does crossing over happen

meiosis 1

how does crossing over work

2 homologs exchange one or more of their alleles

what is the synapse/chiasma

site of crossing over

if one parent had A B alleles and another had a b and they crossed over at the "B/b" alleles what are the new alleles

Ab and aB

what does crossing over yield

recombinant chromatids that have different alleles than parent chromosome

what determines the frequency of crossing over

physical distance between genes

if genes are further apart do they get recombined more frequently or less

more

will two crossovers change anything

no

what is linkage

tendency of genes to be inherited together because they are on the same chromosome

how can you figure our distance between genes

use percentage of recombinant offspring

what is the percentage of recombinant offspring for linked genes and explain

less than 50%. genes that are linked are close together and less likley to be seperated

what is the percentage of recombination for unlinked genes and explain

50% bc genes that are unlinked are far apart and thus likely to be separated