Question

In bacteria, researchers have isolated strains that carry mutations within tRNA genes. These mutations can change the sequence of the anticodon. For example, a normal tRNAtrp gene would encode a tRNA with the anticodon 3'-ACC-5'. A mutation could change this sequence to 3'-CCC-5'. When this mutation occurs, the tRNA still carries a tryptophan at its 3' acceptor stem, even though the anticodon sequence has been altered.

A. How would this mutation affect the synthesis of polypeptides within the bacterium?
B. What does this mutation tell you about the recognition between tryptophanyl-tRNA synthetase and tRNAtrp? Does the enzyme primarily recognize the anticodon or not?

Answer 1

This mutation can potentially change the amino acid sequence of the resulting protein in bacteria. The enzyme tryptophanyl-tRNA synthetase primarily recognizes the anticodon rather than the amino acid it carries.

Step-by-step explanation:

This mutation would affect the synthesis of polypeptides within the bacterium by potentially changing the amino acid sequence of the resulting protein. Even though the tRNA still carries a tryptophan at its 3' acceptor stem, the altered anticodon sequence may pair with different codons on the mRNA. This could lead to the incorporation of a different amino acid during protein synthesis, altering the primary structure of the polypeptide.

This mutation tells us that the enzyme tryptophanyl-tRNA synthetase primarily recognizes the anticodon rather than the amino acid it carries. Despite the change in anticodon sequence, the enzyme can still recognize and bind to the mutated tRNAtrp, allowing the correct amino acid to be attached. This suggests that the recognition between the enzyme and tRNA is primarily based on the anticodon sequence.