We got this task:

There are 3 genes (acb) on one chromosome (linked inheritance). Distance a-c = 12cM, a-b=16cM. Probability for double crossing-over (CO) is 0,6%. Find ratio of genotypes of descendants (AcB/acb X acb/acb).

I don't know whether the 0,6% for double CO is included in the 16% (16cM) probability.

I think it is not, so I got these ratios: No CO and double CO: 42% AcB/acb, 42% acb/acb, 1x CO: 8% Acb/acb, 8% acB/acb


Centi-Morgan (cM) is based on observation not precise measurements. Now since double crossing-overs (and actually any arbitrary even number of crossing-overs) revert gene combination to the parental type, resulting lower recombinant frequency. So in your case since the chance (or the frequency if you wish) for double COs is 0.6%, you have to subtract this from parental genotypes and add it to the recombinants.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.