Question 1

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

Accepted Answer

They cut DNA at specific nucleotide sequences, producing fragments with defined ends.

Question 2

A scientist wants to clone a gene into a plasmid vector. Which property must the plasmid have to be useful for this purpose?

Accepted Answer

It must contain a selectable marker gene, such as antibiotic resistance.

Question 3

Which of the following is a key reason why restriction enzyme recognition sites are often palindromic?

Accepted Answer

Palindromic sequences allow restriction enzymes to bind and cleave both DNA strands at the same position.

Question 4

A researcher uses EcoRI to cut both a plasmid vector and a DNA fragment. What is the advantage of using the same restriction enzyme for both?

Accepted Answer

It ensures that the ends of the DNA fragment and the plasmid are compatible for ligation.

Question 5

Which of the following best explains the purpose of blue-white screening in bacterial cloning?

Accepted Answer

To distinguish between bacterial colonies that contain recombinant plasmids and those that do not.

Question 6

A plasmid vector contains a lacZ gene and an antibiotic resistance gene. After transformation and plating on media with X-gal and antibiotic, which colonies are likely to contain recombinant DNA?

Accepted Answer

White colonies that grow on the antibiotic-containing media.

Question 7

Which of the following vectors would be most appropriate for cloning a 200 kb fragment of human DNA?

Accepted Answer

A bacterial artificial chromosome (BAC)

Question 8

What is the main advantage of using Saccharomyces cerevisiae as a host for eukaryotic gene expression?

Accepted Answer

It can perform posttranslational modifications similar to higher eukaryotes.

Question 9

A cDNA library differs from a genomic library in that a cDNA library:

Accepted Answer

Contains only DNA sequences that are transcribed into mRNA at the time of collection.

Question 10

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

Accepted Answer

The uptake and incorporation of foreign DNA by a bacterial cell.

Question 11

A researcher wants to express a human protein in E. coli. Which type of vector should they use?

Accepted Answer

An expression vector with appropriate prokaryotic regulatory sequences.

Question 12

Which of the following is a critical step in constructing a genomic DNA library?

Accepted Answer

Cutting genomic DNA with restriction enzymes and ligating fragments into vectors.

Question 13

Which of the following equations correctly represents the probability $$P of $$finding a specific 6-base pair restriction site in a random DNA sequence, assuming equal base composition?

Accepted Answer

$$P = (1/4)^6$

Question 14

A Ti plasmid is used to transform plant cells. What is the main function of the T-DNA region in this process?

Accepted Answer

It carries the foreign gene of interest into the plant genome.

Question 15

Which of the following best explains why selectable marker genes are included in cloning vectors?

Accepted Answer

To identify host cells that have successfully taken up the vector.

Question 16

A researcher is screening a DNA library to isolate a specific gene. Which of the following would be most useful for identifying the correct clone?

Accepted Answer

A labeled DNA or RNA probe complementary to the gene of interest.

Question 17

Which of the following statements about blunt and sticky ends is correct?

Accepted Answer

Sticky ends have single-stranded overhangs that can base pair with complementary sequences.

Question 18

Which of the following is a limitation of using standard bacterial plasmids as cloning vectors?

Accepted Answer

They can only accept relatively small DNA fragments, typically up to 15 kb.

Question 19

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

Accepted Answer

It joins DNA fragments by forming phosphodiester bonds between adjacent nucleotides.

Question 20

A researcher is constructing a cDNA library from liver cells. Which enzyme is essential for synthesizing the first DNA strand from mRNA?

Accepted Answer

Reverse transcriptase

Recombinant DNA Technology: Principles and Applications

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