Question 1

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

Accepted Answer

It unzips the DNA double helix and assembles a complementary mRNA strand from the 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

A poly-A tail consisting of many adenines is added.

Question 3

A mutation causes the removal of the 5' cap from an mRNA molecule. What is the most likely consequence for this mRNA during translation?

Accepted Answer

The ribosome will not recognize where to begin translation, so the protein will not be synthesized.

Question 4

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

Accepted Answer

Introns are non-coding regions that are removed, while exons are coding regions that remain in the mature mRNA.

Question 5

Which sequence of events correctly describes the flow of genetic information in a eukaryotic cell?

Accepted Answer

DNA → RNA → Protein

Question 6

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

Accepted Answer

Addition of the poly-A tail

Question 7

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

Accepted Answer

A site (Amino acid site)

Question 8

The start codon for translation in mRNA is always:

Accepted Answer

$$\mathrm{AUG}$$

Question 9

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

Accepted Answer

After one ribosome moves past the start codon, another can bind and begin translation, forming a polyribosome.

Question 10

A patient has a genetic disorder caused by a mutation that changes the stop codon $$\mathrm{UAA} to$$ $$\mathrm{CAA}. $$What is the most likely effect on the resulting protein?

Accepted Answer

The protein will be longer than normal because translation will continue past the normal stop site.

Question 11

Which of the following is NOT a function of the poly-A tail added to eukaryotic mRNA?

Accepted Answer

Helps ribosomes recognize the start codon

Question 12

If a tRNA has the anticodon $$\mathrm{UAC}$$, which mRNA codon will it pair with during translation?

Accepted Answer

$$\mathrm{AUG}$$

Question 13

Which of the following best describes the function of a spliceosome?

Accepted Answer

It removes introns from pre-mRNA and joins exons together.

Question 14

A researcher introduces a mutation that prevents the formation of the ribosome's large subunit. What is the most immediate effect on protein synthesis?

Accepted Answer

Initiation of translation will not be completed, and no polypeptide will be synthesized.

Question 15

Which of the following codons does NOT code for an amino acid and instead signals termination of translation?

Accepted Answer

$$\mathrm{UAA}$$

Question 16

During translation, what is the correct order in which a tRNA moves through the ribosomal sites?

Accepted Answer

A site → P site → E site

Question 17

A protein destined for secretion from the cell will most likely:

Accepted Answer

Be transported in a vesicle to the plasma membrane and released by exocytosis.

Question 18

Which of the following best explains why gene expression is regulated at the level of transcription?

Accepted Answer

Only genes that are transcribed into RNA can be expressed as traits, so controlling transcription controls which proteins are made.

Question 19

Which of the following is true regarding the relationship between codons and amino acids?

Accepted Answer

Each codon consists of three nucleotides and codes for a specific amino acid.

Question 20

A cell is observed to have a mutation in the promoter region of a gene. What is the most likely effect of this mutation?

Accepted Answer

RNA polymerase may not bind properly, so the gene may not be transcribed.

Molecular Biology of the Gene: From DNA to Protein

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