Answer to Question #146049 in Genetics for anonymous

Question

Hybridization of a homozygous dominant and homozygous recessive plant was conducted. What is the probability that the F2 will have the phenotype green, small and spade shaped leaves with pink and rounded fruits?

Answer 1

Suppose that all alleles in genes are in a relationship of complete dominance, then we can assume:

A-Oval shaped leaves

a-spade shaped leaves

B-Pink leaves

b- Green leaves

C- Purple flowers

c- White flowers

D- Rounded fruits

D-Pink fruits

F2- aabbccdd (phenotype big oval shaped yellow leaves, white flowers, and pink fruits)?

P: AABBCCDD x aabbccdd

F1:   AaBbCcDd

To analyze phenotypes, we will use the most technically simple mathematical method.

Mathematical (algebraic) method - the probability of occurrence of any combination of all genotypes in a polyhybrid crossing is equal to the product of the probabilities of genotypes for each of the analyzed genes.

At interbreeding: P AaBbCcDd x AaBbCcDd

Crossing for gene A: Аа × Аа;

F2 for gene A: (¾ А_ + ¼аа)

 

Crossing for gene В: Вb × Вb

F2 for gene В: (¾ В_ + ¼bb)

Crossing for gene C: Cc × Cc

F2 for gene C: (¾ C_ + ¼cc)

 

Crossing for gene D: Dd × Dd

F2 for gene D: (¾ D_ + ¼dd)

 

For definition in F2 aabbccdd is necessary:

aabbccdd = (¼аа) * (¼bb) * (¼cc) * (¼dd) = 1/256 = 0,004%