Question 1

Which of the following best describes the role of transfer RNA (tRNA) during translation?

Accepted Answer

tRNA serves as an adapter molecule that brings specific amino acids to the ribosome by matching its anticodon to the codon on mRNA.

Question 2

What is the function of aminoacyl-tRNA synthetase in protein synthesis?

Accepted Answer

It attaches the correct amino acid to its corresponding tRNA, using energy from ATP.

Question 3

Which region of the tRNA molecule binds to the codon on the mRNA during translation?

Accepted Answer

The anticodon loop, which contains a sequence complementary to the mRNA codon

Question 4

During the elongation phase of bacterial translation, what happens immediately after a peptide bond forms between the amino acids in the A and P sites?

Accepted Answer

The polypeptide chain is transferred to the tRNA in the A site.

Question 5

Which of the following statements about ribosomes is TRUE?

Accepted Answer

Ribosomes are composed of both proteins and rRNAs, and the rRNAs catalyze peptide bond formation.

Question 6

What is the main outcome if a mutation prevents the aminoacyl-tRNA synthetase for lysine from functioning?

Accepted Answer

Lysine will not be incorporated into proteins, leading to incomplete or nonfunctional proteins.

Question 7

Which of the following best explains why the ribosome is considered a ribozyme?

Accepted Answer

Its rRNA catalyzes the formation of peptide bonds during translation.

Question 8

In the context of translation, what is the significance of the 'A', 'P', and 'E' sites on the ribosome?

Accepted Answer

They are sites where tRNAs bind and move through during translation, facilitating the addition of amino acids to the growing polypeptide.

Question 9

Which of the following events occurs during the termination phase of translation?

Accepted Answer

A release factor binds to the stop codon in the A site, causing the polypeptide to be released from the tRNA in the P site.

Question 10

Which of the following post-translational modifications is most likely to affect the activity of an enzyme?

Accepted Answer

Addition of a phosphate group by a kinase

Question 11

A scientist adds radiolabeled leucine to a cell-free translation system. After a short time, the radiolabel is found in polypeptides rather than tRNAs. What does this result support?

Accepted Answer

Aminoacyl-tRNAs transfer their amino acids to growing polypeptides during translation.

Question 12

Which step in bacterial translation requires energy from GTP?

Accepted Answer

Translocation of the ribosome along the mRNA

Question 13

If the anticodon of a tRNA is 5'-UGA-3', which mRNA codon will it recognize?

Accepted Answer

5'-ACU-3'

Question 14

Which of the following is a direct consequence of a mutation that disrupts the ribosome binding site on bacterial mRNA?

Accepted Answer

The small ribosomal subunit will not bind the mRNA, preventing translation initiation.

Question 15

Which of the following best describes the relationship between the structure and function of tRNA?

Accepted Answer

The stem-and-loop structure positions the amino acid attachment site and anticodon at a precise distance, allowing accurate translation of the genetic code.

Question 16

Which of the following is NOT a function of post-translational modifications?

Accepted Answer

Attaching amino acids to tRNAs

Question 17

During translation, what would happen if the E site of the ribosome was nonfunctional?

Accepted Answer

Uncharged tRNAs would not exit the ribosome, potentially stalling translation.

Question 18

Which of the following best explains why the ribosome supports the 'RNA world' hypothesis?

Accepted Answer

The catalytic activity of the ribosome is carried out by rRNA, suggesting ancient catalytic RNAs.

Question 19

Which of the following steps occurs first during the initiation of bacterial translation?

Accepted Answer

The small ribosomal subunit binds to the ribosome binding site on the mRNA.

CH 17 p. 2: Structure and Function of tRNA and Ribosomes: Mechanisms of Translation

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