Which Is True About Proofreading Activity During the Synthesis of Aminoacyl-TRNAs

Multiple Choice

Which is true about proofreading activity during the synthesis of aminoacyl-tRNAs?

A) Proofreading is accomplished as an amino acid enters the active site of the enzyme.Incorrect amino acids are rejected before any reaction occurs.
B) Proofreading occurs just after aminoacyl-adenylate formation.
C) A separate cytosolic proofreading enzyme catalyzes the hydrolysis of incorrect aminoacyl-tRNAs.
D) No proofreading activity is necessary due to the high level of specificity of all aminoacyl-tRNA synthetases.