Question 1

Which of the following best describes a palindrome in the context of DNA restriction sites?

Accepted Answer

A sequence where the 5' to 3' sequence on one strand matches the 5' to 3' sequence on the complementary strand, allowing restriction enzymes to recognize and cut at these sites.

Question 2

What is the primary function of restriction enzymes in bacterial cells?

Accepted Answer

To protect bacteria from foreign DNA, such as viral genomes, by cutting them at specific sequences.

Question 3

Which enzyme is responsible for joining DNA fragments together by forming covalent bonds in the sugar-phosphate backbone?

Accepted Answer

DNA ligase

Question 4

In a gene cloning experiment, why is ampicillin used in the growth medium?

Accepted Answer

To select for bacteria that have successfully taken up the plasmid containing the ampicillin resistance gene.

Question 5

A researcher inserts a gene of interest into the LacZ gene of a plasmid and grows bacteria on X-gal plates. What color will the colonies containing recombinant plasmids appear?

Accepted Answer

White, because the LacZ gene is disrupted and cannot metabolize X-gal.

Question 6

Which of the following best explains why cDNA libraries are used instead of genomic DNA libraries when expressing human genes in bacteria?

Accepted Answer

cDNA libraries contain only the coding sequences without introns, which bacteria cannot process.

Question 7

Which tool would you use to amplify a specific DNA sequence from a small sample for further analysis?

Accepted Answer

Polymerase Chain Reaction (PCR)

Question 8

What is the role of a selectable marker in a plasmid used for cloning?

Accepted Answer

It enables identification of bacteria that have taken up the plasmid by conferring resistance to an antibiotic.

Question 9

Which process is described by the following equation? $$	ext{DNA} ightarrow 	ext{RNA} ightarrow 	ext{Protein} ightarrow 	ext{Trait}$$

Accepted Answer

Central dogma of molecular biology

Question 10

A scientist wants to find a specific gene in a DNA library. Which technique should they use?

Accepted Answer

DNA hybridization with a labeled probe

Question 11

Why do restriction enzymes typically recognize palindromic sequences?

Accepted Answer

Because they allow the enzyme to cut both DNA strands at the same position, creating sticky or blunt ends.

Question 12

Which of the following is a real-world application of gene cloning using recombinant DNA technology?

Accepted Answer

Producing human insulin in bacteria for diabetes treatment.

Question 13

What is the function of methylation in bacterial DNA with respect to restriction enzymes?

Accepted Answer

It protects bacterial DNA from being cut by its own restriction enzymes.

Question 14

Which of the following steps is necessary to create a DNA library from an organism?

Accepted Answer

Cut all nuclear DNA with restriction enzymes and clone fragments into plasmids.

Question 15

If a plasmid contains both a gene of interest and an antibiotic resistance gene, what will happen when bacteria are grown on a plate containing that antibiotic?

Accepted Answer

Only bacteria with the plasmid will survive and grow.

Question 16

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

Accepted Answer

The uptake of recombinant plasmid DNA by bacteria, allowing them to express new genes.

Question 17

Why is reverse transcriptase important in the creation of cDNA libraries?

Accepted Answer

It synthesizes DNA from mRNA templates, allowing cloning of expressed genes without introns.

Question 18

Which of the following is NOT a basic tool used in DNA biotechnology?

Accepted Answer

Microarrays

Question 19

A scientist uses the following steps: cut DNA with EcoRI, insert into plasmid, transform bacteria, and select on ampicillin plates. What is the purpose of the EcoRI enzyme in this process?

Accepted Answer

To cut DNA at a specific palindromic sequence, creating sticky ends for cloning.

Question 20

Which equation represents the process of reverse transcription?

Accepted Answer

$$	ext{RNA} ightarrow 	ext{DNA}$$

Biotechnology: DNA Technology & Genomics – Tools and Applications

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