Mendel 1.Segregation:Equal numbers of A and a .The phenotype resulting from a mutation in a single gene will segregate exactly 2A 2a. Question in Tetradspeak: Does the phenotype segregate2:2? Yes.A and a are alleles of a single gene.Mendel 1. Segregation: Equal numbers of A and a •The phenotype resulting from a mutation in a single gene will segregate exactly 2A : 2a. •Question in Tetradspeak: Does the phenotype segregate2:2? Yes. A and a are alleles of a single gene