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## Calculating % recombination and Mapping distance
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## Calculating % recombination and Mapping distanceHey,
Im confused on how to caluclate the percent recombination and the the mapping distznce in map units. Heres my problem: Consider a cross in Neurospora involving two allelles at the same locus,C and c. The following tetrad patterns were observed CCcc 55 ccCC 40 CcCc 7 cCcC 3 CccC 4 cCCc 5 What is the percent recombination and the approximate distance between the genetic locus and the centromere is? I can't calcualte my percent recombination because im unsure jof the significant difference. But I clacuated my mapping distance by: Getting the sum of all my numbers which is 114,then I added the 4 smaller numbers and I got 19. Now for my calcualteions 19/114=0.166 then divide by 2 since its two genotpyes that are CC and cc. which equals 0.083,then I multiply by 100 which give me 8.33 mapp units. But How do I find my percent recombination from my data? Are there seperate equations for percent recombination and the mapping distance? Thank you ttyl - gymgrl
- Garter
**Posts:**1**Joined:**Sun Mar 23, 2008 4:12 pm
You calculated everything correctly. 8.33 m.u. is also = to 8.33 % which is recombination frequency (1% RF= 1 m.u.).
Your reasoning is not correct though (unless I misunderstood you). You said “19/114=0.166 then divide by 2 since its two genotypes that are CC and cc.” 0.166… or 16.6% is frequency of crossover during meiosis, but only ½ of the product is recombinant. That is why you have to divide by 2; RF = 1/2 of the frequency of crossover during meiosis in this case. - Cat
- King Cobra
**Posts:**635**Joined:**Thu Feb 14, 2008 7:40 pm
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