Question 1

Which experiment provided the first evidence that bacteria can exchange genetic material through direct cell-to-cell contact, and what was the key observation?

Accepted Answer

Lederberg and Tatum's experiment; observation of prototrophs after mixing two auxotrophic E. coli strains

Question 2

In the context of bacterial conjugation, what is the role of the F factor?

Accepted Answer

It is a plasmid that encodes genes for pilus formation and DNA transfer

Question 3

Which of the following best describes generalized transduction?

Accepted Answer

Transfer of any bacterial gene by a bacteriophage during the lytic cycle

Question 4

A U-tube experiment with a fine filter separating two bacterial strains results in no prototrophic colonies. What does this demonstrate about bacterial gene transfer?

Accepted Answer

Direct physical contact is required for conjugation-mediated gene transfer

Question 5

Which of the following is a key difference between Hfr and F⁺ cells in E. coli?

Accepted Answer

Hfr cells have the F factor integrated into the chromosome, allowing high-frequency transfer of chromosomal genes

Question 6

During conjugation, what is the fate of the recipient cell after receiving the F factor from an F⁺ donor?

Accepted Answer

It becomes F⁺

Question 7

Which of the following statements about specialized transduction is correct?

Accepted Answer

It transfers only genes adjacent to the prophage integration site during the lysogenic cycle

Question 8

What is the significance of Hfr conjugation in bacterial genetics?

Accepted Answer

It allows for the mapping of bacterial chromosomes based on the timing of gene transfer

Question 9

A bacterium that can grow on minimal medium without supplements is called:

Accepted Answer

Prototroph

Question 10

Which of the following best explains why only a portion of the bacterial chromosome is usually transferred during Hfr conjugation?

Accepted Answer

Mating is typically interrupted before the entire chromosome can be transferred

Question 11

What is an F′ (F prime) factor?

Accepted Answer

A plasmid that contains the F factor and a portion of the bacterial chromosome

Question 12

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

Accepted Answer

Prevention of gene exchange in prokaryotes

Question 13

If a temperate phage integrates its DNA into the bacterial chromosome, what is the resulting state called?

Accepted Answer

Lysogenic cycle

Question 14

Which gene on the F factor encodes the protein responsible for pilus formation during conjugation?

Accepted Answer

traA

Question 15

A bacterial cell that has incorporated donor DNA through conjugation and expresses new traits is called:

Accepted Answer

Transconjugant

Question 16

Which of the following best describes the sequence of gene transfer during Hfr conjugation?

Accepted Answer

Genes closest to the origin of transfer (oriT) are transferred first in a fixed sequence

Question 17

Which process is most likely responsible for the spread of antibiotic resistance genes among pathogenic bacteria in a hospital setting?

Accepted Answer

Horizontal gene transfer via conjugation

Question 18

Which of the following is a real-world application of bacterial conjugation?

Accepted Answer

Spread of multidrug resistance among clinical isolates

Question 19

If a bacteriophage accidentally packages host bacterial DNA instead of its own, which process is this an example of?

Accepted Answer

Generalized transduction

Question 20

Which of the following equations best represents the probability ($$P) of a $$gene being transferred during Hfr conjugation, if the transfer rate is $$r$$ genes per minute and the mating lasts $$t$$ minutes, assuming genes are transferred linearly from oriT?

Accepted Answer

$$P = r 	imes t$$

Bacterial Genetics: Mechanisms of Gene Transfer and Recombination

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