In dolphins, gray (G) is dominant to black (g), Sleek (S) is dominant to pudgy (
ID: 151773 • Letter: I
Question
In dolphins, gray (G) is dominant to black (g), Sleek (S) is dominant to pudgy (s) and friendly (F) is dominant to mean (f). All loci are autosomal. Pure-breeding black, sleek , mean dolphins were mated to pure-breeding gray, pudgy, friendly dolphins. The F1 were testcrossed. Based on the map below and a coefficient of coincidence of 0.77, determine the frequency of each phenotype in the testcross progeny. Round each answer to 5 decimal digits.
What is the frequency of gray, sleek testcross progeny?
What is the frequency of pudgy, mean testcross progeny?
What is the frequency of gray, friendly testcross progeny?
What is the frequency of pudgy, friendly testcross progeny?
What is the frequency of black, friendly testcross progeny?
What is the frequency of black, pudgy, mean testcross progeny?
What is the frequency of gray, sleek, mean testcross progeny?
What is the frequency of gray, pudgy, friendly testcross progeny?
Color Body Type Disposition 18cM 6cMExplanation / Answer
Answer:
The frequency of gray, sleek testcross progeny =0.08584+0.00416 = 0.09
The frequency of pudgy, mean testcross progeny = 0.02584 + 0.00416 = 0.03
The frequency of gray, friendly testcross progeny = 0.38416+0.00416=0.38832
The frequency of pudgy, friendly testcross progeny = 0.38416 + 0.08584 = 0.47
The frequency of black, friendly testcross progeny = 0.08584 + 0.02584 = 0.11168
The frequency of black, pudgy, mean testcross progeny =0.00416
The frequency of gray, sleek, mean testcross progeny = 0.08584
Tthe frequency of gray, pudgy, friendly testcross progeny =0.38416
Explanation:
Coefficient of coincidence = observed double crossover / Expected double crossover
Expected double crossover = RF between color & body type * RF between body type & disposition
= 18% * 6% = 0.0108
0.77 = ? / 0.0108
Observed double crossover = 0.77 * 0.0108 = 0.008316
gSf / bSf x GsF/ GsF---P1
gSf/GsF--------F1
F1 x gdf/gsf--------------Testcross
gSf/GsF x gsf/gsf--------------Testcross
Class of gametes
Genotype
Frequency of reciprocal pair
Numbers
Frequency of each class
Phenotype
Parental
gSf /gsf
1- all recombinant progeny
1-(0.171684+0.051684+0.008316) = 0.768316
0.38416
Black, Sleek, mean
GsF /gsf
0.38416
Gray, pudgy, friendly
SCO 1
gsF/gsf
RF in region 1 = SCO1 – DCO
SCO1 = 0.18 – 0.008316 = 0.171684
0.08584
Black, pudgy, freindly
GSf/gsf
0.08584
Gray, sleek, mean
SCO 2
gSF/gsf
RF in region 2 = SCO2 – DCO
SCO2 = 0.06 – 0.008316 = 0.051684
0.02584
Black, sleek, freindly
Gsf/gsf
0.02584
Gray, pudgy, mean
DCO
gsf/gsf
Observed DCO
0.008316
0.00416
Black, pudgy, mean
GSF/gsf
0.00416
Gray, sleek, freindly
Class of gametes
Genotype
Frequency of reciprocal pair
Numbers
Frequency of each class
Phenotype
Parental
gSf /gsf
1- all recombinant progeny
1-(0.171684+0.051684+0.008316) = 0.768316
0.38416
Black, Sleek, mean
GsF /gsf
0.38416
Gray, pudgy, friendly
SCO 1
gsF/gsf
RF in region 1 = SCO1 – DCO
SCO1 = 0.18 – 0.008316 = 0.171684
0.08584
Black, pudgy, freindly
GSf/gsf
0.08584
Gray, sleek, mean
SCO 2
gSF/gsf
RF in region 2 = SCO2 – DCO
SCO2 = 0.06 – 0.008316 = 0.051684
0.02584
Black, sleek, freindly
Gsf/gsf
0.02584
Gray, pudgy, mean
DCO
gsf/gsf
Observed DCO
0.008316
0.00416
Black, pudgy, mean
GSF/gsf
0.00416
Gray, sleek, freindly
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