Q: Which of the following equations best represents the hydrolysis of lactose by beta-galactosidase?

$$\text{Lactose} \xrightarrow{\text{beta-galactosidase}} \text{Glucose} + \text{Galactose}$$

Question 1

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

Accepted Answer

Uptake of naked DNA from the environment by a bacterial cell.

Question 2

In Griffith’s experiment with Streptococcus pneumoniae, what was the key finding when mice were injected with a mixture of heat-killed smooth (S) strain and live rough (R) strain bacteria?

Accepted Answer

The mice died, and live smooth (S) strain bacteria were recovered from their bodies.

Question 3

Which of the following is a property of plasmids in bacteria?

Accepted Answer

They are small, circular DNA molecules that replicate independently of the chromosome.

Question 4

A bacterium that has acquired the pBLU plasmid will be able to:

Accepted Answer

Grow on LB/amp/X-gal plates and produce blue colonies.

Question 5

Which of the following equations best represents the hydrolysis of lactose by beta-galactosidase?

Accepted Answer

$$	ext{Lactose} \xrightarrow{	ext{beta-galactosidase}} 	ext{Glucose} + 	ext{Galactose}$$

Question 6

Which plate would you expect to see growth from both transformed and non-transformed E. coli in a transformation experiment?

Accepted Answer

LB

Question 7

What is the main difference between vertical and horizontal gene transfer in bacteria?

Accepted Answer

Vertical gene transfer is the transfer of genes from parent to offspring, while horizontal gene transfer is the transfer of genes between unrelated cells.

Question 8

During conjugation between an F+ cell and an F- cell, what is the outcome?

Accepted Answer

Both cells become F+ cells.

Question 9

Which of the following best describes generalized transduction?

Accepted Answer

Transfer of random bacterial chromosome fragments by a lytic bacteriophage.

Question 10

In specialized transduction, which DNA is packaged into the phage capsid?

Accepted Answer

A combination of viral DNA and a specific piece of bacterial DNA adjacent to the prophage.

Question 11

A hospital isolates a strain of E. coli that is resistant to multiple antibiotics. Which mechanism most likely contributed to the rapid spread of resistance genes among different bacterial species?

Accepted Answer

Horizontal gene transfer via plasmids and transduction.

Question 12

Which of the following is a key step in the laboratory transformation procedure to induce E. coli to take up plasmid DNA?

Accepted Answer

Heat shock at 42°C for 90 seconds.

Question 13

After conjugation between an Hfr cell and an F- cell, what is the most likely outcome for the recipient cell?

Accepted Answer

It remains F- but may acquire new chromosomal genes through recombination.

Question 14

Which of the following best explains why blue colonies appear on LB/amp/X-gal plates in a transformation experiment?

Accepted Answer

The bacteria express beta-galactosidase, which cleaves X-gal to produce a blue product.

Question 15

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

Accepted Answer

Loss of the ability to replicate DNA.

Question 16

Which of the following statements about the role of controls in a transformation experiment is correct?

Accepted Answer

Negative controls confirm that only transformed cells can grow on selective media.

Question 17

Which of the following best describes the mechanism of recombination during transformation?

Accepted Answer

Fragmented DNA from the environment is inserted into the chromosome by recombination.

Question 18

Which of the following is a real-world consequence of horizontal gene transfer in clinical settings?

Accepted Answer

Rapid spread of antibiotic resistance among pathogenic bacteria.

Question 19

Which of the following best describes the difference between generalized and specialized transduction?

Accepted Answer

Generalized transduction transfers random bacterial DNA, while specialized transduction transfers specific genes adjacent to the prophage.

Bacterial Genetics and Horizontal Gene Transfer: Study Notes for Microbiology

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