## How do you know the number of gametes produced from a cross?

**Moderators:** Leonid, amiradm, BioTeam

### How do you know the number of gametes produced from a cross?

I understand that a general formula for

F1 gametes is 2^n,

F2 genotypes is 3^n and

F2 phenotypes would be 2^n,

where n is the number of genes.

However, I am confused how the answers come about, I'm more of a visual learner so I'd benefit more by seeing the different gametes and counting them, math just confuses me.

I was thinking since gametes are haploid then for

a) the potiential gametes would be A and a, which are 2.

Then for b) A,a,B,b which are 4.

And finally c) A,a,B,b,C,c which is 6--but when you do the formula for this one, you get 8? (2^3 = 8 )

I think I am misunderstanding the concept. Would someone please explain this, I have a test coming up so I would really appreciate it, thank you so much in advance!

How many different kinds of F1 gametes, F2 genotypes, and F2 phenotypes would be expected from the following crosses:

(a) AA x aa;

(b) AA BB x aa bb;

(c) AA BB CC x aa bb cc?

F1 gametes is 2^n,

F2 genotypes is 3^n and

F2 phenotypes would be 2^n,

where n is the number of genes.

However, I am confused how the answers come about, I'm more of a visual learner so I'd benefit more by seeing the different gametes and counting them, math just confuses me.

I was thinking since gametes are haploid then for

a) the potiential gametes would be A and a, which are 2.

Then for b) A,a,B,b which are 4.

And finally c) A,a,B,b,C,c which is 6--but when you do the formula for this one, you get 8? (2^3 = 8 )

I think I am misunderstanding the concept. Would someone please explain this, I have a test coming up so I would really appreciate it, thank you so much in advance!

How many different kinds of F1 gametes, F2 genotypes, and F2 phenotypes would be expected from the following crosses:

(a) AA x aa;

(b) AA BB x aa bb;

(c) AA BB CC x aa bb cc?

### Who is online

Users browsing this forum: No registered users and 2 guests