Early geneticists wondered how only four nucleotides can specify the sequence of 20 amino acids in proteins. they hypothesized that there must be a code that linked the nucleotide sequence in a gene to the amino acid sequence in a protein. each nucleotide code is called a codon. today we know that there is a genetic code in which (s) code(s) for each amino acid.

Early geneticists wondered how only four nucleotides can specify the sequence of 20 amino acids in proteins. They hypothesized that there must be a code that linked the nucleotide sequence in a gene to the amino acid sequence in a protein. Each nucleotide code is called a codon. Today we know that there is a genetic code in which nucleotide(s) code(s) for each amino acid.

3

4

1

2

Explanation:

3 is the answer. 43 or 64 is the number of possible 3-letter codes that can be formed.

more than one codon can codes for the same amino acid