Question 1

Which of the following best describes the structure of the typical bacterial genome?

Accepted Answer

One circular chromosome condensed by supercoiling and looping into a nucleoid

Question 2

A bacterial strain is described as leu-. What does this mean about its growth requirements?

Accepted Answer

It requires leucine added to minimal medium to grow

Question 3

Which process involves the direct transfer of genetic material from one bacterial cell to another via physical contact?

Accepted Answer

Conjugation

Question 4

In an interrupted mating experiment, why is a blender used during the process?

Accepted Answer

To separate mating pairs and stop further gene transfer

Question 5

Which of the following is true about Hfr strains in bacterial conjugation?

Accepted Answer

They transfer chromosomal genes at a high frequency to the recipient

Question 6

A bacterial mutant is described as str^r. What does this indicate?

Accepted Answer

It is resistant to streptomycin

Question 7

Which mechanism of genetic exchange in bacteria involves uptake of free DNA from the environment?

Accepted Answer

Transformation

Question 8

If a bacterial cell is described as F+, what does this mean?

Accepted Answer

It contains the F plasmid and can act as a donor in conjugation

Question 9

Which of the following best explains the role of R plasmids in bacterial populations?

Accepted Answer

They code for antibiotic resistance and can be transferred between bacteria

Question 10

During conjugation, what is the fate of the DNA strand transferred from the donor to the recipient?

Accepted Answer

It integrates into the recipient genome via homologous recombination

Question 11

A researcher mixes two auxotrophic E. coli strains: Strain A (met- bio- thr- leu- thi-) and Strain B (met+ bio+ thr+ leu+ thi+). After mixing, rare colonies grow on minimal medium. What is the most likely explanation?

Accepted Answer

Genetic exchange occurred, producing recombinants with wild-type alleles

Question 12

Which equation best represents the exponential growth of bacteria under ideal conditions?

Accepted Answer

$$N = N_0$ 	imes 2^n$$

Question 13

In a mapping experiment, the order of gene transfer is leu+, arg+, met+. If you select for leu+ recombinants, which marker is most likely to be present in the highest frequency among these recombinants?

Accepted Answer

arg+

Question 14

Which of the following statements about plasmids is correct?

Accepted Answer

Plasmids can carry genes for antibiotic resistance and can replicate independently

Question 15

A bacterial cell is described as gal-. What does this mean?

Accepted Answer

It cannot utilize galactose as a carbon source

Question 16

Which of the following is a real-world consequence of horizontal gene transfer via conjugation?

Accepted Answer

Rapid spread of antibiotic resistance among pathogenic bacteria

Question 17

In an interrupted mating experiment, the time of entry for genes is used to map their order on the chromosome. If gene A enters at 5 min, gene B at 10 min, and gene C at 15 min, what is the most likely order of genes?

Accepted Answer

A, B, C

Question 18

Which of the following best describes the function of the F pilus during bacterial conjugation?

Accepted Answer

It facilitates physical contact and DNA transfer between donor and recipient cells

Question 19

A faulty outlooping event in a bacterial cell leads to the formation of an F' plasmid. What is a key feature of this plasmid?

Accepted Answer

It carries the F factor plus a portion of the bacterial chromosome

Question 20

Which of the following is NOT a mechanism of genetic exchange in bacteria?

Accepted Answer

Binary fission

Chapter 6. Class Notes Powerpoint

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