Assume that a chiasma forms between gene loci C and D in 32% of the meioses of a

Question

Assume that a chiasma forms between gene loci C and D in 32% of the meioses of an individual having genotype CDl/cd. The I/ represent two homologous chromosomes that contain the C and D genes: one homolog contains the C and D alleles and the other contains the c and d alleles. You cross this CDl/cd individual to a cdllcd individual and examine the progeny resulting from this testcross. What proportion of the progeny of the testcross will be Cdllcd: a) 4% b) 8% c) 16% d) 32% e) None of the above 2)

Explanation / Answer

2) Chiasma forms between gene loci C and D in 32% of the meioses, so cross-over types of gametes form in 32% of the meioses.

The individual having CD//cd genotype thus will form parental gametes CD and cd in (100-32)=68% meioses and cross-over gametes Cd and cD in 32% cases. The other individual having cd//cd genotype will produce only one type of gamete i.e cd

So four types of genotypes can be formed-

CD//cd, cd//cd=parental type,68% and

Cd//cd, cD//cd=cross-over type,32%

So proportion of progeny having cross-over genotype Cd//cd will be=32/2=16%

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.