Three genes in the lab bug, an insect specially bred for genetics problems, are
ID: 318215 • Letter: T
Question
Three genes in the lab bug, an insect specially bred for genetics problems, are linked as indicated in the following gene map:
-----------------A/a------10 cM-----B/b------------------25 cM-------------------C/c------
Parental AAbbCC and aaBBcc lab bugs are mated to yield an AaBbCc F1 generation. The F1 individuals are then test-crossed with aabbcc lab bugs. Assuming that 1,000 test-cross offspring (the lab bug is very prolific) hatch, predict the number of test-cross offspring exhibiting non-recombinant and recombinant phenotypes. (For simplicity, ignore the possibility of double crossover offspring.)
Type of
Genotype Crossover # Offspring
AabbCc Non-recombinant
aaBbcc Non-recombinant
Aabbcc Recombinant
aaBbCc Recombinant
AaBbcc Recombinant
aabbCc Recombinant
(HINT: Look at the parental generation to see which alleles are linked together.)
**Please write in detail so I can learn from it! Thank you!!
Explanation / Answer
Answer:
Genotype Crossover # Offspring
AabbCc Non-recombinant 325
aaBbcc Non-recombinant 325
Aabbcc Recombinant 125
aaBbCc Recombinant 125
AaBbcc Recombinant 50
aabbCc Recombinant 50
Explanation:
Linked gene configuration= AbC/aBc
Map distance = recombination frequency
Single cross over b/w a & b produces the following progeny in 10/100 * 1000 = 100
ABc/abc = 50
abC/abc=50
Single cross over b/w b & c produces the following progeny in 25/100 * 1000 = 250
Abc/abc= 125
aBC/abc=125
Total recombinants = 100 + 250 = 350
Non-recombinants = 1000-350 = 650
AabbCc=325
aaBbcc=325
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