Question 1

Which of the following statements best describes the main difference between bacterial conjugation and transformation?

Accepted Answer

Conjugation requires direct cell-to-cell contact, while transformation involves uptake of free DNA from the environment.

Question 2

A researcher mixes two auxotrophic E. coli strains, each unable to grow on minimal medium. After incubation, colonies appear on minimal medium. What is the most likely explanation for this observation?

Accepted Answer

Genetic recombination occurred via conjugation, resulting in prototrophic recombinants.

Question 3

Which of the following is a key feature that makes bacteria ideal for genetic studies?

Accepted Answer

They are haploid, so mutations are directly observable without dominance effects.

Question 4

In an interrupted mating experiment, the order of gene transfer is thr, leu, azi, ton, lac, gal. Which gene is closest to the origin of transfer (oriT)?

Accepted Answer

thr

Question 5

Which equation best represents the relationship between cotransduction frequency ($$f) $$and the distance ($$d) $$between two genes?

Accepted Answer

$$f \propto \frac{1}{d}$$

Question 6

A bacterium is resistant to streptomycin due to an R plasmid. If this bacterium is mixed with a sensitive strain and plated on streptomycin-containing media, what is the expected outcome?

Accepted Answer

Only bacteria that have acquired the R plasmid will grow.

Question 7

Which of the following best describes rolling circle replication during bacterial conjugation?

Accepted Answer

A single strand of DNA is transferred to the recipient while the donor synthesizes a replacement strand.

Question 8

What is the outcome when an Hfr cell conjugates with an F− cell?

Accepted Answer

The F− cell may acquire new chromosomal genes but usually remains F−.

Question 9

Which process is most likely to result in a partial diploid (merozygote) bacterial cell?

Accepted Answer

Conjugation with an F′ donor cell.

Question 10

Which of the following statements about generalized transduction is correct?

Accepted Answer

Any bacterial gene can be transferred because DNA packaging is random.

Question 11

A bacteriophage integrates into the E. coli chromosome at a specific site and later excises, sometimes carrying adjacent bacterial genes. What is this process called?

Accepted Answer

Specialized transduction

Question 12

Which of the following is NOT a possible outcome of bacterial conjugation?

Accepted Answer

Recipient cell becomes resistant to antibiotics by generalized transduction.

Question 13

Which of the following best explains why multiple Hfr strains are needed to construct a complete genetic map of E. coli?

Accepted Answer

Each Hfr strain transfers genes in a unique order and direction, covering different regions of the chromosome.

Question 14

Which of the following is true regarding the lysogenic cycle of a temperate bacteriophage?

Accepted Answer

The phage DNA integrates into the host chromosome and can be excised later to enter the lytic cycle.

Question 15

Which of the following best describes the use of selective media in bacterial genetics experiments?

Accepted Answer

It allows only bacteria with specific genotypes to grow, facilitating identification of recombinants.

Question 16

Which of the following is a correct statement about plasmids?

Accepted Answer

They are small, circular, double-stranded DNA molecules that often carry non-essential genes.

Question 17

In a transformation experiment, why are only genes that are closely linked likely to be cotransformed?

Accepted Answer

Because the DNA fragments taken up are short and only contain closely linked genes.

Question 18

Which of the following is a real-world consequence of lateral gene transfer in bacteria?

Accepted Answer

Rapid spread of antibiotic resistance among pathogenic bacteria.

Question 19

Which of the following best describes the function of the relaxosome during bacterial conjugation?

Accepted Answer

It binds to the F plasmid at oriT and nicks one DNA strand to initiate transfer.

Gene Transfer and Mapping in Bacteria and Bacteriophages

Guida di studio - Domande di pratica

Study guide - Flashcard