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Free notes, MCQs, tables & flowcharts for USMLE Step 3 Biochemistry
An investigator studying protein synthesis in human stem cells isolates tRNA molecules bound to mRNA molecules. The isolated tRNA molecules have inosine in the 5' position of the anticodon; of these, some are bound to adenine, some to cytosine, and some to uracil at the 3' position of the mRNA codon. Which of the following properties of the genetic code is best illustrated by this finding?
AUnambiguity
BNon-overlapping
CDegeneracy
DSpecificity of the start codon
ESpecificity of stop codons
A researcher is tracing the fate of C-peptide, a product of preproinsulin cleavage. Which of the following is a true statement regarding the fate of C-peptide?
AC-peptide exits the cells via a protein channel
BC-peptide is further cleaved into insulin
CC-peptide is packaged with insulin in secretory vesicles
DC-peptide is immediately degraded by the proteasome
EC-peptide activates an intracellular signaling cascade
A group of scientists is studying the molecular mechanisms of protein synthesis. In the picture is the theoretical structure for tRNA. Where is the binding site for an amino acid?
AA
BB
CC
DE
ED
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