Question 1

Which of the following best explains how different cell types (e.g., muscle vs. neuron) can arise in a human, even though all cells contain the same DNA sequence?

Accepted Answer

Gene regulation allows selective expression of genes, resulting in different proteins and cell functions.

Question 2

A researcher discovers a gene that produces a functional RNA molecule but is never translated into protein. Which type of gene is this most likely to be?

Accepted Answer

A noncoding RNA gene

Question 3

Which of the following statements about the human genome is correct?

Accepted Answer

Repetitive DNA constitutes approximately 50% of the genome.

Question 4

Which of the following best describes the function of microRNAs (miRNAs) in eukaryotic cells?

Accepted Answer

They regulate gene expression by blocking translation and promoting RNA degradation.

Question 5

During eukaryotic transcription initiation, which of the following events occurs first?

Accepted Answer

TBP binds to the TATA box in the promoter region.

Question 6

A mutation in the AAUAAA sequence of a pre-mRNA would most likely affect which process?

Accepted Answer

Polyadenylation at the 3′ end

Question 7

Which of the following statements about RNA polymerase is TRUE?

Accepted Answer

RNA polymerase does not require helicase to unwind DNA during transcription.

Question 8

A patient is exposed to α-amanitin, a toxin from the death cap mushroom. Which cellular process will be most directly inhibited?

Accepted Answer

Transcription of protein-coding genes by RNA Polymerase II

Question 9

Which of the following best explains why alternative splicing increases protein diversity in humans?

Accepted Answer

It allows different combinations of exons to be included in mature mRNAs, producing multiple proteins from a single gene.

Question 10

Which of the following is a function of the 5′ cap added to eukaryotic mRNA?

Accepted Answer

It protects the mRNA from degradation and is required for nuclear export.

Question 11

A frameshift mutation is most likely to result from which of the following genetic changes?

Accepted Answer

An insertion or deletion of nucleotides not in multiples of three

Question 12

Which of the following best describes the role of aminoacyl-tRNA synthetases in translation?

Accepted Answer

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

Question 13

A scientist is studying a ribosome and observes that it contains both proteins and rRNAs, and catalyzes peptide bond formation. What is the term for an RNA molecule with catalytic activity?

Accepted Answer

Ribozyme

Question 14

Which of the following antibiotics specifically inhibits bacterial RNA polymerase, thereby blocking transcription in prokaryotes?

Accepted Answer

Rifamycin

Question 15

A mutation causes a single nucleotide change that converts a codon for glutamine (CAA) into a stop codon (UAA). What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 16

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

Accepted Answer

The genetic code is universal and redundant.

Question 17

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

Accepted Answer

A site

Question 18

A patient is treated with tetracycline for a bacterial infection. What is the mechanism of action of this antibiotic?

Accepted Answer

It blocks aminoacyl-tRNA binding to the ribosome.

Question 19

Which of the following best explains why polyribosomes are efficient for protein production?

Accepted Answer

They allow multiple ribosomes to simultaneously translate a single mRNA, increasing protein output.

Question 20

A gene contains the following sequence on its coding strand: 5′-ATG GAA TGA-3′. What is the corresponding mRNA sequence (written 5′ to 3′)?

Accepted Answer

$$5'	ext{-}AUG\ GAA\ UGA	ext{-}3'$$

Gene Expression: From DNA to Functional Protein

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