Question 1

Which of the following best describes the function of the 5' cap added to eukaryotic mRNA during processing?

Accepted Answer

It protects the mRNA from nucleases and helps position the mRNA on the ribosome for translation.

Question 2

A mutation changes the GU at the 5' end of an intron to AU. What is the most likely consequence for mRNA processing?

Accepted Answer

The spliceosome will fail to recognize the splice site, leading to retention of the intron.

Question 3

Which of the following is TRUE regarding the genetic code?

Accepted Answer

The code is degenerate, meaning some amino acids are specified by more than one codon.

Question 4

What is the role of the exon junction complex (EJC) in mRNA metabolism?

Accepted Answer

It is required for efficient export of mRNA from the nucleus and influences mRNA degradation.

Question 5

A patient has a mutation in the gene encoding U2 snRNP. Which process will be most directly affected?

Accepted Answer

Recognition of the branch point during splicing of most introns

Question 6

Which of the following sequences signals the addition of the poly(A) tail during mRNA processing?

Accepted Answer

AAUAAA

Question 7

A scientist is studying a eukaryotic mRNA that lacks a 5' cap. Which of the following is a likely consequence?

Accepted Answer

The mRNA will be rapidly degraded and poorly translated.

Question 8

Which of the following best explains why the genetic code is described as 'unambiguous'?

Accepted Answer

Each codon specifies only one amino acid.

Question 9

Which of the following is a function of the poly(A) tail on eukaryotic mRNA?

Accepted Answer

It protects mRNA from nuclease attack and is required for export to the cytoplasm.

Question 10

A researcher mutates the branch point A residue in an intron. What is the most likely effect on splicing?

Accepted Answer

The lariat structure will not form, preventing proper splicing.

Question 11

Which of the following statements about tRNA charging is correct?

Accepted Answer

Each aminoacyl-tRNA synthetase is specific for one amino acid and its corresponding tRNAs.

Question 12

Which of the following best describes the difference between bacterial and eukaryotic mRNA processing?

Accepted Answer

Eukaryotic mRNA undergoes capping, polyadenylation, and splicing, while bacterial mRNA is usually ready for translation immediately after transcription.

Question 13

A mutation in the gene encoding NXF1 would most likely result in which cellular defect?

Accepted Answer

Impaired export of mature mRNA from the nucleus

Question 14

Which of the following is a direct result of alternative splicing?

Accepted Answer

Production of multiple protein isoforms from a single gene

Question 15

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

Accepted Answer

UAA

Question 16

A scientist is studying a mitochondrial gene in mammals and finds that the codon AGA is present. What is the most likely function of this codon in this context?

Accepted Answer

It acts as a stop codon.

Question 17

Which of the following best explains why a triplet code is necessary to encode all 20 amino acids?

Accepted Answer

A triplet code allows for 64 possible codons, which is more than enough for 20 amino acids.

Question 18

Which of the following is a unique feature of eukaryotic translation initiation compared to bacterial translation initiation?

Accepted Answer

Use of methionine as the first amino acid and a greater number of initiation factors (eIFs)

Question 19

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

Accepted Answer

They attach the correct amino acid to its corresponding tRNA using ATP hydrolysis.

Question 20

A mutation causes the loss of the GU-AG rule at the ends of an intron. Which process is most likely to be disrupted?

Accepted Answer

Splicing of the intron by the spliceosome

RNA Processing, Splicing, and Translation: Key Concepts in Eukaryotic Gene Expression

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