Question 1

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

Accepted Answer

A bacterium takes up free DNA from its environment and incorporates it into its genome.

Question 2

Which property is NOT typical of bacterial genomes compared to eukaryotic genomes?

Accepted Answer

Bacterial genomes are usually linear and contain introns.

Question 3

A scientist uses EcoRI to cut both a plasmid and a gene of interest. What feature of EcoRI makes it useful for creating recombinant DNA?

Accepted Answer

EcoRI creates sticky ends by cutting at palindromic sequences.

Question 4

Which of the following equations correctly represents the calculation of the number of possible DNA fragments ($$n) $$generated by a restriction enzyme that recognizes a 6-base pair sequence in a random DNA sequence of length $$L$$?

Accepted Answer

$$n = \frac{L}{4^6$}$$

Question 5

A researcher wants to ensure that a gene is inserted into a plasmid in a specific orientation. Which strategy should they use?

Accepted Answer

Use two different restriction enzymes that create non-compatible sticky ends.

Question 6

Which of the following best explains why plasmids are useful tools in molecular biology?

Accepted Answer

They are small, self-replicating DNA molecules that can carry foreign genes into bacteria.

Question 7

A bacterial cell is exposed to DNA from a lysed cell containing an antibiotic resistance gene. After uptake, the cell survives on antibiotic media. Which process has occurred?

Accepted Answer

Transformation

Question 8

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

Accepted Answer

The rapid spread of antibiotic resistance among pathogenic bacteria.

Question 9

A plasmid contains an ampicillin resistance gene ($$amp^r) $$and a multiple cloning site within the $$lacZ$$ gene. What is the expected phenotype of a bacterial colony with a recombinant plasmid containing a gene inserted into the $$lacZ$$ site, when plated on X-gal and ampicillin?

Accepted Answer

White colonies that are resistant to ampicillin

Question 10

Which of the following best describes the function of DNA ligase in recombinant DNA technology?

Accepted Answer

It seals nicks in the sugar-phosphate backbone, joining DNA fragments together.

Question 11

A researcher digests a plasmid and a gene insert with EcoRI and ligates them together. After transformation, some colonies do not contain the insert. What is the most likely explanation?

Accepted Answer

The plasmid re-ligated without the insert (self-ligation).

Question 12

Which of the following statements about restriction enzymes is correct?

Accepted Answer

They recognize specific palindromic DNA sequences and cut both DNA strands.

Question 13

If a bacterial genome is 4,000,000 base pairs and a restriction enzyme recognizes a 6-base pair sequence, how many fragments are expected after complete digestion? Use the formula $$n = \frac{L}{4^6$}.$$

Accepted Answer

$$n = \frac{4,000,000}{4^6$} = 976.56 \approx 977$$ fragments

Question 14

Which of the following is a key difference between bacterial conjugation and transformation?

Accepted Answer

Conjugation requires direct cell-to-cell contact, while transformation does not.

Question 15

Agarose gel electrophoresis is used in molecular biology to:

Accepted Answer

Separate DNA fragments by size.

Question 16

Which of the following best explains why restriction sites are often palindromic?

Accepted Answer

Palindromic sequences allow restriction enzymes to recognize and cut both DNA strands at the same position.

Question 17

Which of the following is a real-world application of engineered plasmids in medicine?

Accepted Answer

Production of human insulin in bacteria.

Question 18

A scientist wants to determine the orientation of a gene inserted into a plasmid. Which technique would be most useful?

Accepted Answer

Restriction digest with asymmetrically located sites followed by agarose gel electrophoresis.

Question 19

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

Accepted Answer

Binary fission

Question 20

Why is it important to use antibiotic selection when growing bacteria transformed with recombinant plasmids?

Accepted Answer

To ensure that only bacteria containing the plasmid survive and grow.

Genetics of Bacteria: Horizontal Gene Transfer and Recombinant DNA Technology

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