Question 1

Which of the following statements best describes the role of the Kozak sequence in eukaryotic translation initiation?

Accepted Answer

It is a consensus sequence that helps the ribosome identify the correct start codon (AUG) for translation initiation.

Question 2

A mutation changes the third base of a codon from C to U, but the amino acid specified does not change. Which concept explains this phenomenon?

Accepted Answer

Third-base wobble

Question 3

Which of the following best describes the function of aminoacyl-tRNA synthetases?

Accepted Answer

They add the correct amino acid to its corresponding tRNA, a process known as 'charging' the tRNA.

Question 4

Which of the following is a direct consequence of a frameshift mutation caused by the insertion of a single nucleotide in the coding region of a gene?

Accepted Answer

All codons downstream of the insertion are altered, potentially changing every amino acid after the mutation.

Question 5

Which of the following best explains why bacterial ribosomes can begin translating mRNA before transcription is complete, but eukaryotic ribosomes cannot?

Accepted Answer

Bacterial transcription and translation both occur in the cytoplasm, while eukaryotic transcription occurs in the nucleus and translation in the cytoplasm.

Question 6

A scientist synthesizes an artificial mRNA consisting only of repeating U nucleotides (poly(U)). When translated in vitro, which polypeptide will be produced?

Accepted Answer

A polypeptide consisting only of phenylalanine

Question 7

Which of the following is NOT a function of the ribosome during translation?

Accepted Answer

Synthesizing mRNA from a DNA template

Question 8

Which of the following posttranslational modifications is most likely to regulate the activity of a protein by turning it on or off?

Accepted Answer

Phosphorylation by kinases

Question 9

A eukaryotic ribosome is composed of which subunits and rRNAs?

Accepted Answer

40S and 60S subunits with 18S, 5.8S, 28S, and 5S rRNAs

Question 10

Which of the following best describes the process of translation elongation in eukaryotes?

Accepted Answer

The ribosome moves in the 3' direction along the mRNA, recruiting charged tRNAs to the A site, forming peptide bonds, and translocating the ribosome.

Question 11

Which of the following codons is a stop codon in the universal genetic code?

Accepted Answer

UGA

Question 12

A mutation in the gene encoding insulin prevents cleavage of the pre–amino acid segment from preproinsulin. What is the most likely consequence?

Accepted Answer

Insulin will not be properly processed and will remain nonfunctional.

Question 13

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

Accepted Answer

The genetic code is universal with very few exceptions, mainly in mitochondria.

Question 14

Which of the following best explains why methionine is not always the first amino acid in mature eukaryotic proteins?

Accepted Answer

Methionine is often removed posttranslationally from the N-terminus of the protein.

Question 15

Which of the following is a property of polyribosomes (polysomes) in bacteria?

Accepted Answer

They are groups of ribosomes translating the same mRNA simultaneously.

Question 16

Which of the following best describes the role of the signal sequence in protein sorting?

Accepted Answer

It acts as an address label, directing the protein to the endoplasmic reticulum and then to its final cellular destination.

Question 17

Which of the following is true regarding the reading frame of mRNA during translation?

Accepted Answer

The reading frame is set by the start codon and is read continuously in triplets with no gaps.

Question 18

Which of the following best explains why there are fewer tRNA genes than codons specifying amino acids?

Accepted Answer

Some tRNAs can recognize multiple codons due to third-base wobble.

Question 19

Which of the following is a real-world application of the universality of the genetic code?

Accepted Answer

Using bacteria to produce human insulin for medical use.

The Molecular Biology of Translation: Study Notes for Genetics Students

Study Guide - Practice Questions

Study Guide - Flashcards