In parakeets, two autosomal genes pairs control the production of feather pigmentation. The M allele codes for an enzyme that is required for the synthesis of melanin, which produces the blue pigment and Y allele codes for an enzyme required for the synthesis of yellow pigment. A bird breeder mates two green birds and produces offspring that are green, blue, yellow and white.

1. What are the genotypes of the parents?

2. What are the genotypes of the offspring?

3. In what proportions would you expect to find the offspring?

Genotypes of parents MmYy and MmYy

genotypes of offsprings MMYY, MMYy, MMyy, MmYY, MmYy, Mmyy,

mmYY, mmYy, mmyy

offspring proportions green : blue : yellow : white

9 : 3 : 3 : 1

Explanation:

M = melanin produces blue pigment

Y = yellow pigment

parental phenotype green x green

parental genotype MmYy MmYy

meiosis

gamtetes MY My mY my MY My mY my

offpring genotype

gametes MY My mY my

MY MMYY MMYy MmYY MmYy

green green green green

My MMYy MMyy MMYy Mmyy

green blue green blue

mY MmYY MmYy mmYY mmYy

green green yellow yellow

my MmYy Mmyy mmYy mmyy

green blue yellow white

offspring phenotype green blue yellow white

offsring proportion 9 3 3 1

Further explanation: as crossing two green parents is giving four different phenotypes shows that blue and yellow genes are co dominant and that parents are heterozygotes