Question

Disc 2, Bb# 3 In the morning glory plant, three genes are linked as follows: 20 m.u 30 m.u A morning glory plant with the genotype BB gg DD was crossed to a morning glory plant of genotype bb GG dd. The F1 progeny was testcrossed to a b g d/bg d plant. A. Assume no interference, what genotypic classes will be found in the progeny and the frequencies if there are 1000 progeny? B. Assume 20% interference, what genotypic classes will be found in the progeny and the frequencies if there are 1000 progeny?

please show all work clearly

Answer 1

Answer:

BgD/BgD x bGd/bGd----Parents

BgD/bGd ------------------F1

BgD/bGd x bgd/bgd

A).

Expected double crossover progeny = 20% * 30% = 0.06

Class of gametes	Phenotype	Frequency of reciprocal pair	Numbers	Frequency of each class	Number of progeny frequency * 1000 = %
Parental	BgD	1- all recombinant progeny	1-(0.14+0.24+0.06) = 0.56	0.28	280 (BgD/bgd)
	bGd			0.28	280 (bGd/bgd)
SCO 1	BGd	RF in region 1 = SCO1 – DCO	SCO1 = 0.2 – 0.06 = 0.14	0.07	70 (BGd/bgd)
	bgD			0.07	70 (bgD / bgd)
SCO 2	Bgd	RF in region 2 = SCO2 – DCO	SCO2 =0.3 – 0.06 = 0.24	0.12	120 (Bgd/bgd)
	bGD			0.12	120 (bGD / bgd)
DCO	BGD	(RF in region 1) * (RF in region 2)	0.06	0.03	30 (BGD/bgd)
	Bgd			0.03	30 (bgd/bgd)

B).

Interference = 1- COC

20% or 0.2 = 1 – COC

COC = 1 – 0.2 = 0.8

COC = Observed double crossover progeny / Expected double crossover progeny

Expected double crossover progeny = 20% * 30% = 0.06

0.8 = Observed double crossover progeny / 0.06

Observed double crossover progeny = 0.06 * 0.8 = 0.048

Class of gametes	Phenotype	Frequency of reciprocal pair	Numbers	Frequency of each class	Number of progeny frequency * 1000 = %
Parental	BgD	1- all recombinant progeny	1-(0.152+0.252+0.048) = 0.548	0.274	274 (BgD/bgd)
	bGd			0.274	274 (bGd/bgd)
SCO 1	BGd	RF in region 1 = SCO1 – DCO	SCO1 = 0.2 – 0.048 = 0.152	0.076	76 (BGd/bgd)
	bgD			0.076	76 (bgD / bgd)
SCO 2	Bgd	RF in region 2 = SCO2 – DCO	SCO2 =0.3 – 0.048 = 0.252	0.126	126 (Bgd/bgd)
	bGD			0.126	126 (bGD / bgd)
DCO	BGD	(RF in region 1) * (RF in region 2)	0.048	0.024	24 (BGD/bgd)
	Bgd			0.024	24 (bgd/bgd)