Phenotype and genotype?

Question

Construct a Punnett square showing both the genotype and phenotype ratios possible if 2 heterozygous brown-eyed individuals with dimpled chins were to have children. Needs to be 4x4. Assume both independent assortment and segregation are occurring.

Can someone help me pls?

Answer 1

Assuming that brown eyes (B) and dimpled chins(D) are dominant:

Parents   BbDd        X      BbDd

gametes   BD, Bd, bD, bd           BD, Bd, bD, bd

Punnet square:

           BD    |    Bd   |   bD  |  bd

BD |  BBDD  | BBDd | BbDD | BbDd

Bd   | BBDd  | BBdd |  BbDd | Bbdd

bD   | bbDD  | BbDd  |  bbDD | bbDd

bd   |  BbDd  |  Bbdd  |  bbDd  |  bbdd

Phenotype Ratios : 9 Brown Eyed and dimpled chins

                                  3 Brown Eyed and non dimpled chins

                                  3  Non brown eyed and dimpled chins

                                  1 Non brown eyed and non dimpled chin

Hope this helps!

Answer 2

Go here for an example of how to set up a Punnett square for two genes, with two alleles each:

http://www.dwm.ks.edu.tw/bio/activelearn...

Remember, because the genes are independently assorting you will have equal frequencies of all possible gametes.