Q: Which equation best represents the rolling circle replication mechanism during plasmid transfer in conjugation?

$$\mathrm{dsDNA} \xrightarrow{\text{nick at oriT}} \mathrm{ssDNA} + \mathrm{displaced~strand}$$

Question 1

Which of the following best describes the process of bacterial transformation?

Accepted Answer

Uptake of free extracellular DNA from the environment by a bacterium

Question 2

A researcher exposes a bacterial culture to UV light, causing DNA damage. Later, some bacteria acquire new genetic traits from DNA fragments in the medium. Which horizontal gene transfer mechanism is most likely responsible?

Accepted Answer

Transformation

Question 3

Which of the following is TRUE regarding the fate of DNA after horizontal gene transfer in bacteria?

Accepted Answer

Transferred DNA can be degraded, replicate independently, or integrate by homologous recombination

Question 4

During conjugation, which structure is essential for the transfer of plasmid DNA between bacterial cells?

Accepted Answer

Sex pilus (conjugation pilus)

Question 5

Which equation best represents the rolling circle replication mechanism during plasmid transfer in conjugation?

Accepted Answer

$$\mathrm{dsDNA} \xrightarrow{	ext{nick at oriT}} \mathrm{ssDNA} + \mathrm{displaced~strand}$$

Question 6

A bacterium receives DNA via a bacteriophage that accidentally packages host DNA instead of viral DNA. What is this process called?

Accepted Answer

Generalized transduction

Question 7

Which of the following statements about Hfr strains is correct?

Accepted Answer

Hfr strains have the F plasmid integrated into their chromosome

Question 8

What is the main difference between specialized and generalized transduction?

Accepted Answer

Generalized transduction transfers DNA from any part of the bacterial genome, while specialized transduction transfers only DNA adjacent to the prophage insertion site

Question 9

Which of the following best describes an episome?

Accepted Answer

A plasmid that can integrate into the host chromosome

Question 10

A bacterial cell receives a plasmid carrying antibiotic resistance genes via conjugation. What is the most likely outcome for the population if the antibiotic is present?

Accepted Answer

The plasmid spreads rapidly, and most cells become resistant

Question 11

Which of the following is a function of the tra genes found on the F plasmid?

Accepted Answer

Encode proteins for the formation of the sex pilus and DNA transfer

Question 12

What is the role of RecA protein during transformation in bacteria?

Accepted Answer

Facilitates homologous recombination between incoming ssDNA and the host chromosome

Question 13

Which of the following best describes a transposon?

Accepted Answer

A mobile genetic element that contains a transposase gene and additional genes, often antibiotic resistance genes

Question 14

Which equation best represents the duplication of the target sequence during transposition?

Accepted Answer

$$	ext{Target~DNA} \xrightarrow{	ext{transposase}} 	ext{Transposon~insertion} + 	ext{Duplicated~target~sequence}$$

Question 15

A mutation in the gene encoding transposase would most likely affect which process?

Accepted Answer

Transposition of mobile genetic elements

Question 16

Which of the following statements about bacterial genetic adaptation is correct?

Accepted Answer

Genetic adaptation can result from both small changes (mutations) and large changes (horizontal gene transfer)

Question 17

Which of the following is NOT a mechanism of horizontal gene transfer in bacteria?

Accepted Answer

Binary fission

Question 18

If a transposon inserts into a gene, what is the most likely consequence?

Accepted Answer

The gene is disrupted, potentially blocking transcription or translation

Question 19

Which of the following best explains why viruses cannot be placed on the universal phylogenetic tree?

Accepted Answer

Viruses do not have ribosomal RNA genes used for phylogenetic analysis

Question 20

Which of the following is TRUE regarding the F’ plasmid?

Accepted Answer

It is an F plasmid that has excised imperfectly, carrying a portion of the host chromosome

Horizontal Gene Transfer and Genetic Adaptation in Bacteria: Study Notes for Microbiology

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