Three loci M, K and Q are located on the same chromosome in order as just stated

Question

Three loci M, K and Q are located on the same chromosome in order as just stated (i.e locus K is in the middle). We found that the frequency of recombinants between M and K is 0.30 and the frequency of recombinants between K and Q it is 0.10. What is the expected frequency of double recombinants (i.e. double crossovers) between M and Q (i.e. when one recombination occurs between M and K and one recombination occurs between K and Q, simultaneously)?

If only 0.024 of progeny of the testcross M/m.K/k.Q/q x m/m.k/k.q/q are double crossovers, what is the coefficient of coincidence (c.o.c.)?

What is the interference?

Explanation / Answer

Three loci M, K and Q ... K and Q, simultaneously)?
Calculation of DCO frequency:
As the interference or COC is not mentioned here, condiering that the interference is 0, hence the
COC = 1.
COC = Prop of ODCO/ Prop of EDCO.
=> 1 = Prop of ODCO/ (0.30 X 0.10) => DCO = 1 X 0.30 X 0.10 = 0.03.

If only 0.024 of progeny of the testcross M/m.K/k.Q/q x m/m.k/k.q/q are double crossovers, what is the coefficient of coincidence (c.o.c.)?

What is the interference?

COC = Prop of ODCO/ Prop of EDCO. = 0.024/0.03= 0.8.

AS, COC + interference = 1, interference = 1- COC => 1-0.8 = 0.2.

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