Consider the following three genotypes for the production of the protein melanin. The dominant allele (A) produces normal skin color, but the recessive allele (a) inhibits melanin production, resulting in an albino (lack of pigment in the skin).

AA         Aa         aa

Which of the above genotypes represents an individual who is homozygous for the melanin trait? 

Which of the genotypes listed in question one contains one maternal allele and one paternal allele? Explain your answer.

Which genotype(s) listed in question one represent(s) an individual that is heterozygous?

Would there be a phenotypic different between AA and Aa when the genes are expressed? Explain your answer.