Two plants are heterozygous for two gene pairs (Ab/aB) whose loci are linked 25

Question

Two plants are heterozygous for two gene pairs (Ab/aB) whose loci are linked 25 mu apart. Assuming crossover occurs during the formation of both male and female gametes and the A and B alleles are dominant, explain how these phenotypic ratios are determined. A-B- 33/64 A-bb 15/64 aaB- 15/64 aabb 1/64
Chapter 5 Chromosome up to 25 pe nt. each, the mete proportions would be the following: 3/8 Ab; 3/8 a B: 1/8 AB, 1/8 ab combine the gametes from each parent (they are the same) and arrive at the following frequency: A B 33164; A bb 15164. aa 15164; aabb 1164

Explanation / Answer

Determine frequency of gametes (recombinant gametes have to add up to 25%). parental: 3/8 Ab, 3/8 aB

recombinant: 1/8 AB, 1/8 ab [Note: Parental gametes =75% (3/4)]

There are two gametes (Ab and aB)

Therefore, ¾ x ½ = 3/8 for each gamete.

Recombinant gametes = 25% for two gametes (AB and ab)

Therefore each gamete is ¼ x ½ = 1/8. (same ratios for male and female)

Finally combine these using forked branch diagram and getting following result :

33/64 A- B, 15/64 A-bb, 15/64 aaB, 1/64 aabb

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

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