The mRNA formed from the repeating tetranucleotide UUAC incorporates only three amino acids, but the use of UAUC incorporates four amino acids. Why?

Key Concepts

Tetranucleotide Structure

A tetranucleotide consists of four nucleotides in a specific sequence. In the context of mRNA, the sequence of nucleotides determines the codons, which are groups of three nucleotides that code for specific amino acids. The arrangement of these nucleotides affects how many unique codons can be formed, influencing the number of amino acids incorporated during protein synthesis.

Codon Usage

Codons are sequences of three nucleotides in mRNA that correspond to specific amino acids during translation. The genetic code is degenerate, meaning that multiple codons can code for the same amino acid. The difference in the number of amino acids incorporated from the two mRNA sequences (UUAC vs. UAUC) is due to the variation in codon combinations that can be formed from the respective tetranucleotides.

Amino Acid Incorporation

The process of incorporating amino acids into a growing polypeptide chain during translation is dictated by the mRNA sequence. Each unique codon corresponds to a specific amino acid, and the total number of distinct codons determines how many different amino acids can be added. In this case, the tetranucleotide UUAC produces fewer unique codons than UAUC, leading to the incorporation of fewer amino acids.