Question 1

Which of the following statements best describes the role of aminoacyl-tRNA synthetases in protein synthesis?

Accepted Answer

They attach amino acids to their corresponding tRNA molecules using ATP hydrolysis.

Question 2

A mutation changes the DNA sequence from GAA to GUA in the gene encoding hemoglobin. What type of mutation is this, and what is its likely effect?

Accepted Answer

Missense mutation; substitution of valine for glutamic acid.

Question 3

During translation, which site on the ribosome is responsible for holding the tRNA carrying the growing polypeptide chain?

Accepted Answer

P (peptidyl) site

Question 4

Which of the following best explains the wobble hypothesis?

Accepted Answer

It permits flexibility in pairing between the third base of the codon and the corresponding base of the tRNA anticodon.

Question 5

Which of the following codons is NOT a stop codon in eukaryotic translation?

Accepted Answer

AUG

Question 6

A patient’s cells have a mutation that changes a stop codon to a sense codon, resulting in a longer than normal protein. What type of mutation is this?

Accepted Answer

Nonstop mutation

Question 7

Which of the following is TRUE regarding the energy requirements for polypeptide elongation during translation?

Accepted Answer

Polypeptide elongation involves hydrolysis of at least four high-energy phosphoanhydride bonds per amino acid added.

Question 8

Which of the following best describes the difference between monocistronic and polycistronic mRNAs?

Accepted Answer

Monocistronic mRNAs encode a single polypeptide, while polycistronic mRNAs encode several polypeptides with related functions.

Question 9

Which of the following is a real-life example of posttranslational processing?

Accepted Answer

The removal of the N-terminal 'pre' sequence from preproinsulin to form proinsulin.

Question 10

Which of the following statements about tRNA charging is correct?

Accepted Answer

Aminoacyl-tRNA synthetases attach amino acids to tRNAs via an ester bond, using ATP hydrolysis.

Question 11

A frameshift mutation is most likely to result from which of the following genetic changes?

Accepted Answer

An insertion or deletion of one or two base pairs.

Question 12

Which of the following is required for the correct recognition of the start codon during eukaryotic translation initiation?

Accepted Answer

A Kozak sequence surrounding the AUG codon.

Question 13

Which of the following best describes the direction in which mRNA is read during translation?

Accepted Answer

5' to 3'

Question 14

Which of the following statements about the role of inosine in tRNA is correct?

Accepted Answer

Inosine is often found in the wobble position of the anticodon and can pair with U, C, or A.

Question 15

Which of the following steps in translation does NOT require hydrolysis of ATP or GTP?

Accepted Answer

Peptide bond formation between amino acids at the A and P sites.

Question 16

Which of the following is TRUE about the 5' and 3' untranslated regions (UTRs) of eukaryotic mRNA?

Accepted Answer

They are essential for mRNA function and vary in length.

Question 17

Which of the following is a function of the poly(A)-binding protein (PABP) in eukaryotic translation?

Accepted Answer

It binds the poly(A) tail and interacts with eIF4G to facilitate translation initiation.

Question 18

Which of the following is the correct sequence of events during the elongation phase of translation?

Accepted Answer

Aminoacyl tRNA binding, peptide bond formation, translocation

Question 19

A mutation changes an amino acid codon to a stop codon, resulting in a truncated protein. What is this type of mutation called?

Accepted Answer

Nonsense mutation

Gene Expression: Protein Synthesis (Translation) – Chapter 19 Study Notes

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