Question

Assuming there is no crossover, and alleles A and B undergo independent assortment, which of the following are true for an egg from an individual with the genotype AaBb?

• A. All eggs are AaBb
• B. 1/4 AABB + 1/2 AaBb + 1/4 aabb
• C. 1/4 AB + 1/4 Ab 1/4 aB + 1/4 ab
• D. 1/2 AB + 1/2 ab
• E. 1/2 Aa + 1/2 Bb

Answer 1

The correct option is C 1/4 AB + 1/4 Ab 1/4 aB + 1/4 ab

The total number of different types of gametes possible for a given genotype = 2${}^n$ (where n is number of heterozygous genes).

For the genotype AaBb, n is 2

So different type of gametes i.e. eggs with different genotypes possible = 2${}^2$

= 4

Different genotypes possible for the egg are: AB, Ab, aB, ab

The probability of egg with AB genotype = 1/4

The probability of egg with Ab genotype = 1/4

The probability of egg with aB genotype = 1/4

The probability of egg with ab genotype = 1/4

So, the correct answer is '1/4 AB + 1/4 Ab + 1/4 aB + 1/4 ab'.