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Help with inheritence question... Biology!

Coat colour in mice is controlled by two genes, each with two alleles. The genes are on
different chromosomes.
One gene controls the pigment colour. The presence of allele A results in a yellow and black
banding pattern on individual hairs, producing an overall grey appearance called agouti. Mice with
the genotype aa do not make the yellow pigment and are, therefore, black.
The other gene determines whether any pigment is produced. The allele D is required for
development of coat colour. Mice with the genotype dd produce no pigment and are called
albino.

Question : Give all the possible genotypes for a black mouse.

I don't know how to work this out
Reply 1
Avatar for TheFactor
TheFactor
Original post by FREYA2898
Coat colour in mice is controlled by two genes, each with two alleles. The genes are on
different chromosomes.
One gene controls the pigment colour. The presence of allele A results in a yellow and black
banding pattern on individual hairs, producing an overall grey appearance called agouti. Mice with
the genotype aa do not make the yellow pigment and are, therefore, black.
The other gene determines whether any pigment is produced. The allele D is required for
development of coat colour. Mice with the genotype dd produce no pigment and are called
albino.

Question : Give all the possible genotypes for a black mouse.

I don't know how to work this out

A and D are dominant alleles. AA, Aa and AA would all result in black, aa would result in it being yellow as it is recessive.
So answer would be, AA, AA, Aa.
Reply 2
Avatar for joostan
joostan
13
Original post by FREYA2898
Coat colour in mice is controlled by two genes, each with two alleles. The genes are on
different chromosomes.
One gene controls the pigment colour. The presence of allele A results in a yellow and black
banding pattern on individual hairs, producing an overall grey appearance called agouti. Mice with
the genotype aa do not make the yellow pigment and are, therefore, black.
The other gene determines whether any pigment is produced. The allele D is required for
development of coat colour. Mice with the genotype dd produce no pigment and are called
albino.

Question : Give all the possible genotypes for a black mouse.

I don't know how to work this out


You simply need to list each possible combination of A,a,DA,a,D and dd, that give rise to a black mouse.

You might like to break this down into first considering what affects the banding pattern, and then what affects pigment i.e. consider the A,aA,a gene first, then the D,dD,d gene.


Original post by TheFactor
A and D are dominant alleles. AA, Aa and AA would all result in black, aa would result in it being yellow as it is recessive.
So answer would be, AA, AA, Aa.


Erm, you might wanna re-read the question. . . aaaa gives rise to black.
(edited 8 years ago)
Reply 3
Avatar for TheFactor
TheFactor
Oh, must've got it wrong. I hastily answered it while trying to hold my bladder before going to the toilet.
Reply 4
Avatar for FREYA2898
FREYA2898
OP
5
Original post by TheFactor
A and D are dominant alleles. AA, Aa and AA would all result in black, aa would result in it being yellow as it is recessive.
So answer would be, AA, AA, Aa.



Thanks for answering but I found the answer now
(ii) a^ha^h BB, a^haBB, a^ha^h Bb, a^haBb;;(allow 1 mark for 2 or 3 correct answers)
I still don't know how you get this :frown:
Reply 5
Avatar for FREYA2898
FREYA2898
OP
5
Original post by TheFactor
Oh, must've got it wrong. I hastily answered it while trying to hold my bladder before going to the toilet.


Thanks for answering but I found the answer now (ii) a^ha^h BB, a^haBB, a^ha^h Bb, a^haBb;; (allow 1 mark for 2 or 3 correct answers)
I still don't know how you get this :frown:
Reply 6
Avatar for joostan
joostan
13
Original post by FREYA2898
Thanks for answering but I found the answer now (ii) a^ha^h BB, a^haBB, a^ha^h Bb, a^haBb;; (allow 1 mark for 2 or 3 correct answers)
I still don't know how you get this :frown:


What is the superscript hh notating?
It's been a while since I did stuff like this but the only thing I remember a superscript for was sex-linked alleles. Also your DD has morphed into a BB.

It should be clear that you need two recessive alleles, aaaa to get a black mouse from the description given.
So you can fix the first two letters in the genotype aaaa and then you can find the alleles of the other gene in the normal way.

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