Question 1

Which of the following best describes the role of tRNA during translation?

Accepted Answer

tRNA carries amino acids to the ribosome and matches them to the coded mRNA message using its anticodon.

Question 2

What is the function of the aminoacyl-tRNA synthetase enzyme in translation?

Accepted Answer

It attaches the correct amino acid to its corresponding tRNA using ATP hydrolysis: $$	ext{Amino acid} + 	ext{tRNA} + 	ext{ATP} ightarrow 	ext{Aminoacyl-tRNA} + 	ext{AMP} + 2	ext{P}_i$$

Question 3

During translation, which ribosomal site holds the tRNA carrying the growing polypeptide chain?

Accepted Answer

P site

Question 4

Which of the following statements about the genetic code and tRNA is correct?

Accepted Answer

Wobble allows some tRNAs to recognize more than one codon due to flexible base pairing at the third codon position.

Question 5

A mutation changes the codon 5'-GGC-3' in mRNA to 5'-GGA-3'. What is the likely effect on the protein produced?

Accepted Answer

The protein will have glycine at this position, as both codons code for glycine due to the degeneracy of the genetic code.

Question 6

Which of the following best explains why certain antibiotics can inhibit bacterial protein synthesis without affecting eukaryotic cells?

Accepted Answer

Bacterial ribosomes are smaller and have different molecular compositions, allowing antibiotics to selectively target them.

Question 7

What is the main function of the ribosome during translation?

Accepted Answer

To facilitate the specific coupling of tRNA anticodons with mRNA codons and catalyze peptide bond formation.

Question 8

Which of the following events occurs during the elongation stage of translation?

Accepted Answer

Amino acids are added one by one to the C-terminus of the growing polypeptide chain.

Question 9

What triggers the termination of translation in a ribosome?

Accepted Answer

A release factor binds to a stop codon (UAG, UAA, or UGA) in the A site, causing hydrolysis of the bond between the polypeptide and tRNA.

Question 10

Which of the following best describes a polyribosome (polysome)?

Accepted Answer

A group of ribosomes simultaneously translating a single mRNA molecule, increasing the efficiency of protein synthesis.

Question 11

In eukaryotic cells, what determines whether a ribosome will be free in the cytosol or bound to the endoplasmic reticulum (ER)?

Accepted Answer

The presence of a signal peptide on the growing polypeptide chain.

Question 12

Which of the following post-translational modifications can occur to a newly synthesized polypeptide?

Accepted Answer

Addition of sugars, lipids, or phosphate groups to certain amino acids.

Question 13

Why is the hydrolysis of GTP important during translation?

Accepted Answer

It provides energy for several steps, including the formation of the initiation complex, codon recognition, and translocation during elongation.

Question 14

A tRNA has the anticodon 3'-UCU-5'. Which mRNA codons can it recognize due to wobble base pairing?

Accepted Answer

5'-AGA-3' and 5'-AGG-3'

Question 15

Which of the following is a key difference between translation in bacteria and eukaryotes?

Accepted Answer

In bacteria, translation and transcription are coupled and can occur simultaneously, while in eukaryotes, they are separated by the nuclear envelope.

Question 16

Which of the following best describes the direction in which a polypeptide is synthesized during translation?

Accepted Answer

From the N-terminus (amino end) to the C-terminus (carboxyl end).

Question 17

A researcher mutates the signal peptide sequence of a protein that is normally secreted from a eukaryotic cell. What is the most likely result?

Accepted Answer

The protein will be synthesized in the cytosol and remain there, failing to enter the endomembrane system.

Question 18

Which of the following is true regarding ribosomal RNA (rRNA) in the ribosome?

Accepted Answer

rRNA is the main constituent of the A and P sites and catalyzes peptide bond formation, acting as a ribozyme.

Question 19

Which of the following best describes the consensus sequence in a sequence logo for ribosome binding sites?

Accepted Answer

It shows the most common base at each position, but does not indicate the relative frequency of each base.

Translation: The RNA-Directed Synthesis of Polypeptides

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