Apentix/AP Biology/Unit 6: Gene Expression and Regulation/Question
AP Biologyhardmcq1 pt

Researchers find that heavily purified large ribosomal subunits retain peptide bond forming activity even after most subunit proteins are stripped away, while isolated ribosomal proteins show no such activity. Which conclusion follows?

A.Transfer RNA catalyzes its own charging inside the depleted subunit
B.Messenger RNA folds into the enzyme that catalyzes its own translation
C.The catalytic center resides in ribosomal RNA, making peptide bond formation an RNA-driven reaction
D.Small subunit proteins take over peptide bond duty when large subunit proteins depart

Explanation

Core Concept

Activity surviving protein extraction points to the component that remained: rRNA. Structural work places the peptidyl transferase center among nucleotides of 23S rRNA with no protein side chains close enough to participate. The ribosome therefore qualifies as a ribozyme, supporting arguments that RNA catalysis preceded protein enzymes.

Correct Answer

CThe catalytic center resides in ribosomal RNA, making peptide bond formation an RNA-driven reaction

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