Chapter 12, Problem 39A

Summary Introduction

To determine:

Substitution in the last codon generally does not result in changing the amino acid.

Introduction : 

The codon is a sequence 3 nucleotides, which is responsible for coding 1 amino acid. A single codon codes for one amino acid, but a single amino acid can be coded by multiple codons.

Explanation of Solution

The changes in the third base of a codon generally result in silent mutation. Hence, the amino acid coded by it does not changes. For example, all the DNA codons having T in first position and C in second position codes for serine. All TC_ codons would result in addition of serine only. The codon in third position causes less diversity in amino acid sequence as the first codon and the second are more important in determining the amino acid.