Question 1

Which of the following best describes the role of RNA polymerase during transcription?

Accepted Answer

It synthesizes a complementary mRNA strand from a DNA template.

Question 2

During mRNA processing in eukaryotic cells, which of the following modifications occurs at the 3' end of the pre-mRNA?

Accepted Answer

Addition of a poly-A tail

Question 3

A mutation causes the loss of the promoter region of a gene. What is the most likely consequence?

Accepted Answer

RNA polymerase will not bind, and transcription will not initiate.

Question 4

Which of the following sequences is the correct order of events in gene expression from DNA to protein in a eukaryotic cell?

Accepted Answer

Transcription → mRNA processing → Translation → Protein folding

Question 5

Which of the following statements about introns and exons is correct?

Accepted Answer

Introns are removed from pre-mRNA, and exons are joined together to form mature mRNA.

Question 6

A scientist observes that a certain mRNA molecule degrades rapidly in the cytoplasm. Which processing step was most likely defective?

Accepted Answer

Addition of the poly-A tail

Question 7

During translation, which site in the ribosome does the incoming aminoacyl-tRNA first bind?

Accepted Answer

A site (aminoacyl site)

Question 8

Which of the following codons signals the start of translation and which amino acid does it code for?

Accepted Answer

AUG; methionine

Question 9

A patient has a genetic disorder caused by a mutation that introduces a premature stop codon (UAG) in the middle of a gene. What is the most likely effect on the protein product?

Accepted Answer

The protein will be truncated and likely nonfunctional.

Question 10

Which of the following best explains why multiple ribosomes can translate a single mRNA molecule simultaneously?

Accepted Answer

Ribosomes can attach to the mRNA at different points, forming a polyribosome complex.

Question 11

If a tRNA has the anticodon sequence $$5'	ext{UAC}3'$$, which mRNA codon will it recognize and what amino acid will it carry?

Accepted Answer

$$5'	ext{AUG}3'$$; methionine

Question 12

Which of the following is NOT a function of the 5' cap added to eukaryotic mRNA?

Accepted Answer

It codes for the first amino acid in the protein.

Question 13

A researcher is studying a protein that is secreted from the cell. Which of the following best explains how the cell 'knows' to export this protein?

Accepted Answer

The first few amino acids in the polypeptide act as a signal sequence directing the protein for secretion.

Question 14

Which of the following best describes the relationship between codons and anticodons?

Accepted Answer

Codons are sequences of three nucleotides on mRNA, and anticodons are complementary sequences on tRNA.

Question 15

Which of the following is true regarding the directionality of mRNA synthesis during transcription?

Accepted Answer

mRNA is synthesized in the $$5' \rightarrow 3'$$ direction.

Question 16

A cell is observed to have a buildup of unprocessed pre-mRNA in the nucleus. Which cellular component is most likely malfunctioning?

Accepted Answer

The spliceosome

Question 17

Which of the following best explains why not all DNA in a gene codes for a protein?

Accepted Answer

Some regions, called introns, are non-coding and are removed during mRNA processing.

Question 18

Which of the following is a correct description of the three main stages of translation?

Accepted Answer

Initiation: assembly of ribosome and mRNA; Elongation: polypeptide chain grows; Termination: release of polypeptide at stop codon.

Question 19

A genetic disease is caused by a mutation that prevents the addition of the 5' cap to mRNA. Which of the following is a likely consequence?

Accepted Answer

The ribosome will not recognize where to begin translation.

Question 20

Which of the following best describes the function of ribosomal RNA (rRNA) in the ribosome?

Accepted Answer

It forms the structural and catalytic core of the ribosome, facilitating peptide bond formation.

Molecular Biology of the Gene: From DNA to Protein

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