Question 1

Which of the following statements best describes a key difference between DNA replication in eukaryotic and prokaryotic cells?

Accepted Answer

Eukaryotic cells have multiple origins of replication on each chromosome, while prokaryotic cells typically have a single origin of replication.

Question 2

During transcription in prokaryotes, which of the following is TRUE regarding the role of sigma factors?

Accepted Answer

Sigma factors help RNA polymerase recognize promoter regions and initiate transcription.

Question 3

Given the nucleotide sequence 5'-AUGGCUACU-3' of an mRNA, what is the resulting amino acid sequence after translation?

Accepted Answer

$$	ext{Met-Ala-Thr}$$

Question 4

Which of the following best explains the function of an inducer in the lac operon model?

Accepted Answer

An inducer binds to the repressor, preventing it from binding to the operator and allowing transcription.

Question 5

Which of the following is a consequence of a nonsense mutation in a gene?

Accepted Answer

The mutation introduces a premature stop codon, resulting in a truncated protein.

Question 6

Which of the following statements about viral replication is correct?

Accepted Answer

DNA viruses typically replicate in the host cell nucleus, while RNA viruses often replicate in the cytoplasm.

Question 7

In the context of gene expression, what is the role of an activator protein?

Accepted Answer

An activator protein binds to the promoter to enhance the binding of RNA polymerase and increase transcription.

Question 8

Which of the following best describes the lytic cycle of a bacteriophage?

Accepted Answer

The phage replicates its DNA and immediately lyses the host cell to release new virions.

Question 9

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

Accepted Answer

Ribosome

Question 10

A mutation changes the codon UAU (tyrosine) to UAA. What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 11

Which of the following best describes the difference between positive-sense and negative-sense RNA viruses?

Accepted Answer

Positive-sense RNA viruses have genomes that can be directly translated into proteins by host ribosomes.

Question 12

Which of the following scenarios would most likely result in a non-functioning protein?

Accepted Answer

A frameshift mutation near the start of the coding sequence

Question 13

Which of the following is TRUE regarding the control of gene expression in prokaryotes?

Accepted Answer

Operons allow multiple genes to be regulated together under a single promoter.

Question 14

Which of the following is a function of the lac operon in E. coli?

Accepted Answer

It enables the cell to metabolize lactose when glucose is absent.

Question 15

Which of the following best describes a missense mutation?

Accepted Answer

A mutation that changes one amino acid to another in the protein sequence.

Question 16

Which of the following is a consequence of the lysogenic cycle in bacteriophages?

Accepted Answer

Integration of phage DNA into the host genome, allowing the phage to be replicated with the host cell.

Question 17

Which of the following is TRUE about the structure of viruses?

Accepted Answer

Viruses may have either DNA or RNA, but not both, as their genetic material.

Question 18

Which of the following is a real-world example of horizontal gene transfer in bacteria?

Accepted Answer

A bacterium acquiring antibiotic resistance genes via conjugation.

Question 19

Which of the following best describes the role of repressors in gene regulation?

Accepted Answer

Repressors bind to the operator region to block transcription by RNA polymerase.

Question 20

Which of the following is a likely outcome of a frameshift mutation in a coding region?

Accepted Answer

The reading frame is altered, resulting in a completely different and likely nonfunctional protein.

Cellular Processes in Microorganisms and Viral Genetics: Study Notes for Microbiology

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