Answer
A DNA molecule has 4 bases (A, T, C, G). A sequence of only two bases to define a particular amino acid has a total of $4^{2} = 16$ possible combinations.
Because there are 20 different amino acids in proteins, we need a sequence of 3 bases or $4^{3} = 64$ combinations.
Because this number is greater than 20, some of the sequences are redundant; i.e, they define the same amino acids.
Work Step by Step
A DNA molecule has 4 bases (A, T, C, G). A sequence of only two bases to define a particular amino acid has a total of $4^{2} = 16$ possible combinations.
Because there are 20 different amino acids in proteins, we need a sequence of 3 bases or $4^{3} = 64$ combinations.
Because this number is greater than 20, some of the sequences are redundant; i.e, they define the same amino acids.
