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Wild-type strains of E. coli have a tRNA with a 5-GUA-3 anticodon that recognize

ID: 67572 • Letter: W

Question

Wild-type strains of E. coli have a tRNA with a 5-GUA-3 anticodon that recognizes the UAC codon for tyrosine. We can represent this tRNA as GUA-tRNATyr. Suppose you isolated a strain of E. coli in which a mutation changed the anticodon in this tRNA to 5-CUA-3 (creating CUA-tRNATyr). Answer the following questions about translation elongation in each strain. For each answer, type in “yes” or “no”.

Will the wildtype tRNA recognize a normal UAC codon in the A site?

Will the mutant tRNA recognize a normal UAC codon in the A site?

Will the wildtype tRNA recognize a stop codon in the A site?

Will the mutant tRNA recognize a stop codon in the A site?

Will peptide bond formation occur with the wildtype tRNA bound in the A site?

Will peptide bond formation occur with the mutant tRNA bound in the A site?

Will the normal, wildtype protein be produced in the wildtype strain?

Will the normal, wildtype protein be produced in the mutant strain?

Explanation / Answer

Will the wildtype tRNA recognize a normal UAC codon in the A site?

Ans. Yes

Will the mutant tRNA recognize a normal UAC codon in the A site?

Ans. No

Will the wildtype tRNA recognize a stop codon in the A site?

Ans. No

Will the mutant tRNA recognize a stop codon in the A site?

Ans. Yes

Will peptide bond formation occur with the wildtype tRNA bound in the A site?

Ans. Yes

Will peptide bond formation occur with the mutant tRNA bound in the A site?

Ans. Yes

Will the normal, wildtype protein be produced in the wildtype strain?

Ans. Yes

Will the normal, wildtype protein be produced in the mutant strain?

Ans. No