Question

The P and Q genes of a plant are 20 m.u. apart. A PP qq and a pp QQ individual cross, and the F1 cross with each other to produce the F2. The P and p, and Q and q alleles are completely dominant and recessive, and there are no interactions between genes P and Q. What phenotypic ratio would you expect in the F2

Answer 1

Answer:

66 P_ Q_: 9 P_ qq: 9 pp Q_: 16 pp qq

Explanation:

As the genes are 20 m.u apart, recombination frequency between P & Q genes will be 20% (As 1% recombination = 1 m.u).

Parental cross \rightarrow PP QQ x pp qq

Parental gametes \rightarrow PQ, pq

F1 \rightarrow Pp Qq

F1 gametes \rightarrow PQ (Frequency = 0.4), pq (Frequency = 0.4), Pq (Frequency = 0.1), pQ (Frequency = 0.1) (As non-recombinant gametes frequency will be 0.8 & recombinant gametes frequency will be 0.2)

See the attached table.