Question

In guinea pigs, dark hair (D) is dominant over light hair (d) and curly hair (C) is dominant over smooth hair (c). Complete a dihybrid cross for parents with the genotypes: DdCc × DdCc and answer the following in complete sentences.

Describe how you would set up a Punnett square for this cross.
List the likelihood of each possible offspring genotype.
List the likelihood of each possible offspring phenotype.

Answer 1

I tried to make it as short as possible, though I did get it off from another question, so, my sincerest apologies...

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1.) "It should be laid down in a table of two entries. On the top entry, the possible alleles of one of the parents, and on the other entry, the possible alleles of the other parent, which will be the same as both have the same genotype."

2.) "To identify that all possible genotypes have a 1/8 likelihood to happen, besides the genotypes that are homozygous for both alleles (whether dominant or recessive on both traits, or dominant on one trait and recessive on the other) which have a 1/16 likelihood to happen, and those that are equal to the parents (dihybrid) with a 1/4 likelihood to happen.

DDCC, 1/16; DDCc, 1/8; DdCC, 1/8; DDcc, 1/16; DdCc, 1/4; Ddcc, 1/8; ddCC, 1/16; ddCc, 1/8; ddcc, 1/16."

3.) "Dark and curly hair corresponds to 9/16 of all the offspring. These traits are dominant, and, therefore, are the ones that are present depending solely on the presence of one dominant allele on each trait.Dark and smooth hair have a likelihood of 3/16 - all those that are homozygous recessive for smooth hair but still have, at least, one dominant allele for dark hair.Light and curly hair have a likelihood of 3/16 - all those that are homozygous recessive for light hair but still have, at least, one dominant allele for curly hair.Light and smooth hair have a 1/16 likelihood to occur, which corresponds to the only possible full homozygous recessive genotype."