Early geneticists wondered how only four nucleotides could specify the sequence of 20 amino acids in proteins. Today we know that there is a genetic code in which nucleotide(s) code(s) for each amino acid.

Early geneticists wondered how only four nucleotides could specify the sequence of 20 amino acids in proteins. Today we know that there is a genetic code in which 3 nucleotide(s) code(s) for each amino acid.

Explanation:

64 or 43 is the number of possible 3-letter codes which is more than the number of amino acids. Hence, the code can thus be redundant. It has been seen that there is more than one codon that codes for the same amino acid in some cases, .

Hence, Early geneticists wondered how only four nucleotides could specify the sequence of 20 amino acids in proteins. Today we know that there is a genetic code in which 3 nucleotide(s) code(s) for each amino acid.

answer:

sequence 1- deletion

                  2- duplication

                  3- insertion

                  4- substitute

                  5- inversion