Protein Synthesis

Each gene contains the instructions that determine the sequence of amino acids in a single polypeptide. (Recall that a protein consists of one or more polypeptides). As described in Section 3.6.4, each sequence of three nucleotides, which is called a codon, codes for one amino acid. The four nucleotides can form codons in 43 = 64 ways. Since there are only 20 amino acids, most can be coded by more than one codon. Thus, it is said that the code is degenerate. In addition, there is one codon to indicate START, the beginning of a gene, and several to indicate STOP at the end. The START codon also indicates the amino acid methionine, making it the only codon with two purposes. Table 6.2 is a complete list of codons with their corresponding amino acids.

TABLE 6.2 mRNA Coding Dictionary

Second Position

TABLE 6.2 mRNA Coding Dictionary

First Position

Was this article helpful?

0 0

Post a comment