Question 1

Which of the following best describes a key difference between transcription in prokaryotes and eukaryotes?

Accepted Answer

In eukaryotes, transcription requires the processing of pre-mRNA, including splicing, capping, and polyadenylation, whereas prokaryotic mRNA is often ready for translation immediately after transcription.

Question 2

A scientist discovers a small, double-stranded RNA molecule in a eukaryotic cell that is processed from a long hairpin precursor and is involved in gene silencing. Which type of RNA is this most likely to be?

Accepted Answer

miRNA

Question 3

Which of the following is a major consequence of horizontal gene transfer among bacteria?

Accepted Answer

Acquisition of antibiotic resistance genes, leading to the spread of resistance in bacterial populations

Question 4

A researcher is using 16S rRNA gene sequencing to identify an unknown bacterial isolate. Why is rRNA particularly useful for bacterial classification?

Accepted Answer

rRNA genes contain both conserved and variable regions, allowing for comparison across broad and narrow taxonomic groups.

Question 5

Which of the following best describes a silent mutation?

Accepted Answer

A mutation that changes a codon but does not alter the amino acid sequence of the protein.

Question 6

Which of the following statements about the structure of a virus is correct?

Accepted Answer

Viruses are composed of a protein capsid that encloses their genetic material, which can be either DNA or RNA.

Question 7

During the lytic cycle of a bacteriophage, which of the following events occurs first after the phage attaches to the bacterial cell?

Accepted Answer

Injection of phage DNA into the host cell

Question 8

A patient is infected with a virus that enters the host cell, integrates its genome into the host DNA, and remains dormant for years before reactivating. Which viral infection cycle does this describe?

Accepted Answer

Lysogenic cycle

Question 9

Which of the following best describes the function of siRNA in eukaryotic cells?

Accepted Answer

siRNA is derived from exogenous double-stranded RNA and guides the degradation of complementary mRNA, leading to gene silencing.

Question 10

Which of the following scenarios is an example of horizontal gene transfer?

Accepted Answer

A bacterium receives a plasmid carrying antibiotic resistance genes from another bacterium via conjugation.

Question 11

A missense mutation in a gene results in which of the following outcomes?

Accepted Answer

A change in a single amino acid in the protein sequence.

Question 12

Which of the following best describes the process of translation?

Accepted Answer

The assembly of amino acids into a polypeptide chain using the information encoded in mRNA.

Question 13

A virus with an envelope infects a human cell. Which of the following is a likely step in its entry process?

Accepted Answer

Fusion of the viral envelope with the host cell membrane, allowing the viral genome to enter the cytoplasm.

Question 14

Which of the following is NOT a typical component of a virus?

Accepted Answer

Ribosomes

Question 15

Which of the following best explains why 16S rRNA gene sequencing is a powerful tool for bacterial identification?

Accepted Answer

The 16S rRNA gene is highly conserved among all bacteria, but contains hypervariable regions that allow for species-level discrimination.

Question 16

A nonsense mutation in a gene would most likely result in:

Accepted Answer

A truncated protein due to the introduction of a premature stop codon.

Question 17

Which of the following best describes the process of conjugation in bacteria?

Accepted Answer

Transfer of DNA from one bacterium to another via a pilus.

Question 18

Which of the following statements about miRNA is correct?

Accepted Answer

miRNA is processed from endogenous hairpin RNA precursors and regulates gene expression by binding to complementary mRNA sequences.

Question 19

A virus infects a eukaryotic cell and immediately begins replicating its genome and producing new viral particles, leading to rapid cell lysis. Which type of infection is this?

Accepted Answer

Acute (lytic) infection

Question 20

Which of the following best describes the role of the promoter region in transcription?

Accepted Answer

It is the DNA sequence where RNA polymerase binds to initiate transcription.

Microbiology Study Guide: Genetics, RNA, Viruses, and Mutations

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