In an experiment, erythrocyte precursor cells are incubated in a medium containing radiolabeled cysteine. These radiolabeled cysteine residues are attached to their appropriate tRNAs by the enzyme aminoacyl-tRNA synthetase. The bound cysteine residues are then chemically modified to form alanine. The end product of this reaction is a tRNA molecule that contains the cysteine anticodon but is mischarged with alanine. Which of the following is most likely to occur to this alanine residue during polypeptide synthesis of alpha-hemoglobin?

Question

In an experiment, erythrocyte precursor cells are incubated in a medium containing radiolabeled cysteine.  These radiolabeled cysteine residues are attached to their appropriate tRNAs by the enzyme aminoacyl-tRNA synthetase.  The bound cysteine residues are then chemically modified to form alanine.  The end product of this reaction is a tRNA molecule that contains the cysteine anticodon but is mischarged with alanine.  Which of the following is most likely to occur to this alanine residue during polypeptide synthesis of alpha-hemoglobin?

Quizplus · Accepted Answer

Eductional Objective: The sequence of amino acids in a growing polypeptide chain is dictated by the interaction of the mRNA codon with the tRNA anticodon.  tRNA that is mischarged with the incorrect amino acid (and not corrected by aminoacyl-tRNA synthetase proofreading) will incorporate the wrong amino acid into the growing polypeptide chain.

In an Experiment, Erythrocyte Precursor Cells Are Incubated in a Medium