Question 1

Which factor is responsible for bringing aminoacyl-tRNA to the A site of the ribosome during elongation in prokaryotes?

Accepted Answer

EF-Tu

Question 2

During translation elongation, what is the correct sequence of tRNA movement through the ribosomal sites?

Accepted Answer

A site → P site → E site

Question 3

Which of the following best describes the role of EF-G in translation elongation?

Accepted Answer

It promotes translocation of the ribosome along the mRNA.

Question 4

What is the function of peptidyl transferase during translation?

Accepted Answer

It transfers the growing polypeptide chain from the tRNA in the P site to the amino acid on the tRNA in the A site.

Question 5

Which antibiotic mimics aminoacyl-tRNA and causes premature chain termination during translation?

Accepted Answer

Puromycin

Question 6

In the ribosome, what is the state of the tRNA in the E site?

Accepted Answer

It is uncharged after releasing its amino acid.

Question 7

Which event must occur before EF-G can bind to the ribosome during elongation?

Accepted Answer

Release of EF-Tu from the A site

Question 8

What is the consequence of a mutation that prevents GTP hydrolysis by EF-Tu?

Accepted Answer

Aminoacyl-tRNA cannot be released into the A site, stalling elongation.

Question 9

Which of the following best explains why EF-Tu-GTP and EF-G-GTP can compete for the A site?

Accepted Answer

Both factors mimic the structure of tRNA.

Question 10

During translation, which ribosomal subunit contains the peptidyl transferase center?

Accepted Answer

Large subunit (50S or 60S)

Question 11

A mutation in the gene encoding RF1 would most likely affect which stage of translation?

Accepted Answer

Termination

Question 12

Which of the following equations correctly represents the hydrolysis of GTP by EF-Tu during tRNA delivery?

Accepted Answer

$$\mathrm{GTP} + \mathrm{H}_2\mathrm{O} \rightarrow \mathrm{GDP} + \mathrm{P_i}$$

Question 13

Which process is blocked by the antibiotic puromycin, and what is the result?

Accepted Answer

Peptidyl transfer; premature release of the polypeptide

Question 14

What would happen if a tRNA lacking an anticodon entered the A site?

Accepted Answer

It would be rejected and not participate in peptide bond formation.

Question 15

Which factor is required for the release of the completed polypeptide chain during translation termination?

Accepted Answer

RF1 or RF2

Question 16

If the ribosome fails to translocate after peptide bond formation, what is the immediate consequence?

Accepted Answer

The A site remains occupied and elongation stalls.

Question 17

Which of the following best describes the molecular mimicry used by translation factors?

Accepted Answer

Translation factors resemble tRNA to bind ribosomal sites.

Question 18

Which step in translation elongation is directly powered by GTP hydrolysis?

Accepted Answer

Translocation of the ribosome

Question 19

A patient is treated with an antibiotic that prevents EF-G from binding to the ribosome. What is the most likely effect on protein synthesis?

Accepted Answer

Ribosome cannot translocate, stalling elongation.

Question 20

Which of the following is true regarding the movement of the ribosome during translation?

Accepted Answer

The small subunit shifts first relative to the mRNA, followed by the large subunit.

Mechanisms of Translation: Elongation and Termination in Prokaryotes and Eukaryotes

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