You have a male Yellow Labrador Retriever with a brown nose

You have a male Yellow Labrador Retriever with a brown nose that you are going to breed and your extraordinarily-picky partner desperately wants Chocolate Lab puppies. However, the only female mates to which you have access are all Black Labs. Luckily, your friend works for a genetics laboratory and has offered to determine the genotypes of the Black Labs for you. a) Which Black Lab genotype, if available, would maximize the chances of getting Chocolate Lab puppies and b) what other phenotypes might you expect in the litter? SHOW YOUR WORK!

Solution

male Yellow Labrador Retriever with a brown nose that you are going to breed and your extraordinarily-picky partner desperately wants Chocolate Lab puppies. However, t

he only female mates to which you have access are all Black Labs.

Luckily, your friend works for a genetics laboratory and has offered to determine the genotypes of the Black Labs for you.

a)Which Black Lab genotype, if available, would maximize the chances of getting Chocolate Lab puppies and

)what other phenotypes might you expect in the litter? SHOW YOUR WORK!

Coat color of Labrador Retrievers (Black, brown (chocolate), or yellow) is controlled by two different genes.

B=Black or b=brown

the second gene regulates whether the color pigment will actually be deposited in the hair, and is either \"E\" = permits pigment deposition, or

\"e\" = prevents pigment deposition.

The possible gene types for Labrador Retrievers are shown below.

Gene Types

Coat Color

Nose Color

EEBB

Black

Black

EeBB

Black

Black

EEBb

Black

Black

EeBb

Black

Black

eeBB

yellow

Black

eeBb

yellow

Black

eebb

yellow

brown

EEbb

brown (chocolate)

brown

Eebb

brown (chocolate)

brown

Lab that has at least one \"B\" and one \"E\" (BBEE, BBEe, BbEE, or (BbEe) will be Black.

Lab that has two \"b\'s\" and at least one \"E\" (bbEE or bbEe) will be brown.

male Yellow Labrador Retriever with a brown nose------ GENOTYPE --- bbee

female ----- Black Labs. -------GENOTYPE --- BbEe

BE

Be

bE

be

be

BEbe

Bebe

bE be

brown (chocolate)

be be

be

BEbe

Bebe

bE be

brown (chocolate)

be be

1/4 of offspring’s will be chocolate

Gene Types	Coat Color	Nose Color
EEBB	Black	Black
EeBB	Black	Black
EEBb	Black	Black
EeBb	Black	Black
eeBB	yellow	Black
eeBb	yellow	Black
eebb	yellow	brown
EEbb	brown (chocolate)	brown
Eebb	brown (chocolate)	brown