Question

For Evolution & Genetics

Analyzing patterns of Mendelian inheritance

A poodle named “Choco” with brown, curly fur is in love with poodle “Glitter” that has golden, straight fur. In poodles, Black fur is dominant to golden fur and curly fur is recessive to straight fur. Both our poodles here are true-breeding (homozygous).

1) Determine the genotype and phenotype of the F1 offspring of Choco and Glitter. What are all the possible combinations of alleles in the gametes for F1 offspring.

2) Give the genotypic and phenotypic ratio for the offspring of the cross between two F1 generations (Show your Punnett square for full credit)

3) What percentage of the F2 generations will resemble exactly like their grandma ‘Glitter’?

Answer 1

Poodle Choco- Brown curly hair

Poodle Glitter - golden straight hair

Black fur is dominant over golden fur.

For black fur , gene we are considering is B

For golden fur, gene is b

Straight fur is dominant over curly fur

For straight fur, gene is S

For curly fur , gene is s.

1- now since both poodles are Homozygous means

BBss- choco with black fur and curly hair

bbSS - glitter with golden fur and straight hair

BBss× bbSS

F1 generation- BbSs BbSs BbSs BbSs

Phenotype- black fur with straight hair

Genotype- BbSs

possible combination of alleles in F1 offspring is BbSs

BB× bb

Bb Bb Bb Bb

ss× SS

Ss Ss Ss Ss

2- BbSs × BbSs cross between F1 generations

Gametes from this cross- BS Bs bS bs

Cross shown in a Punnett square in photo.

Phenotypic ratio- 9:3:3:1

Genotypic ratio- 1:2:2:1:4:1:2:2:1

c- the percentage of F2 that would look same like Glitter- 1/16 ×100

= 6.25

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