Gametes produced?

[RHONDAROBINSON]

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Can someone help me understand this question? If a cell with a genotype SsYyRr undergo meiosis, how many types of gametes will be producted? Assume that the S,Y,and R genes are on different chromosome.

Thanks in advance

Rhonda

 

[nitrolegs]

Can someone help me understand this question? If a cell with a genotype SsYyRr undergo meiosis, how many types of gametes will be producted? Assume that the S,Y,and R genes are on different chromosome.

Thanks in advance

Rhonda

well lets see, assuming all alleles are independently segregating, we can have:

SYR
sYR
SyR
SYr
syR
Syr
sYr
syr

or 2x2x2 = 8.

 

[RHONDAROBINSON]

Could you explain please. Thanks

Rhonda

 

[nitrolegs]

the cell undergoing meiosis is heterozygous for 3 genes, S Y and R (for each gene, you have a dominant and a recessive allele). when you form the haploid gametes, you can only have one allele for each gene. because your cells is heterozygous for all 3 genes, you can create a total of 8 different combinations of gametes or 2^3. however if your cell was SSYYRR, you can only create one type of gamete, SYR. same goes with a cell that was ssyyrr (gamete will be syr). if you had SSRrYy, you can make 1x2x2=4 different gametes (SRY, Sry, SrY, and SRy). get it?