Question 1

Which of the following best describes the main difference between a genomic library and a cDNA library?

Accepted Answer

A genomic library contains all the DNA sequences of an organism, including introns and regulatory regions, while a cDNA library contains only the expressed genes (exons) as mRNA converted to DNA.

Question 2

Which feature of a plasmid vector is essential for selecting bacteria that have successfully taken up the plasmid?

Accepted Answer

Antibiotic resistance gene

Question 3

A researcher wants to overexpress a human insulin gene in mammalian cells. Which promoter should they use for high, constitutive expression?

Accepted Answer

Cytomegalovirus (CMV) promoter

Question 4

Which of the following best explains why E. coli is commonly used as a host for recombinant DNA experiments?

Accepted Answer

It divides rapidly, is easy to manipulate genetically, and can efficiently take up plasmid DNA.

Question 5

Which method is most appropriate for introducing a linearized transgene into a fertilized mouse egg to generate a transgenic animal?

Accepted Answer

Microinjection into the male pronucleus

Question 6

In the context of gene knockout using homologous recombination in mice, what is the primary role of the neomycin resistance (NeoR) cassette?

Accepted Answer

To allow positive selection of cells where the targeting vector has integrated by conferring antibiotic resistance

Question 7

Which of the following statements about CRISPR-Cas9 gene editing is correct?

Accepted Answer

It uses a guide RNA to direct the Cas9 nuclease to a specific DNA sequence for targeted editing.

Question 8

A scientist wants to silence a gene in cultured mammalian cells for a short period. Which tool would be most appropriate?

Accepted Answer

Small interfering RNA (siRNA)

Question 9

Which of the following best describes the function of Cre recombinase in conditional knockout mouse models?

Accepted Answer

It excises DNA sequences flanked by loxP sites, allowing for tissue-specific or inducible gene knockout.

Question 10

Which of the following equations correctly represents the reduction in chromosome number during meiosis?

Accepted Answer

$$2n \rightarrow n$$

Question 11

A mouse line is engineered to have exon 2 of a gene flanked by loxP sites. What is the expected outcome when this mouse is crossed with a mouse expressing Cre recombinase under a tissue-specific promoter?

Accepted Answer

Exon 2 will be deleted only in tissues where the promoter is active.

Question 12

Which of the following is a key advantage of using inducible Cre-loxP systems (e.g., CreERT2) in mouse models?

Accepted Answer

They provide temporal control over gene knockout, enabling gene deletion at a chosen time point.

Question 13

Which of the following best explains why the insertion of foreign DNA into the ampicillin resistance gene of pBR322 abolishes resistance to ampicillin?

Accepted Answer

The insertion disrupts the coding sequence, preventing the production of functional resistance protein.

Question 14

Which of the following is a real-world application of recombinant DNA technology in medicine?

Accepted Answer

Production of human insulin in bacteria for diabetes therapy

Question 15

A scientist uses lipofection to introduce a plasmid encoding green fluorescent protein (GFP) into mammalian cells. What is the most direct evidence that the transfection was successful?

Accepted Answer

Cells exhibit green fluorescence under a fluorescence microscope.

Question 16

Which of the following steps is unique to the generation of knockout mice using the embryonic stem cell approach, compared to pronuclear injection?

Accepted Answer

Selection of ES cells with homologous recombination using positive and negative selection markers

Question 17

Which of the following best describes the role of the packaging plasmid in lentiviral vector production?

Accepted Answer

It provides viral proteins necessary for assembling infectious viral particles, but does not carry the gene of interest.

Question 18

Which of the following is a potential outcome when a gene knockout is lethal in mice?

Accepted Answer

The knockout mice die before birth, and only heterozygotes or wild-type are observed among offspring.

Question 19

Which of the following best describes the function of small interfering RNAs (siRNAs) in gene regulation?

Accepted Answer

They guide the RNA-induced silencing complex (RISC) to degrade complementary mRNA, leading to gene silencing.

Recombinant DNA Technology and Transgenic Models: Applications and Methods

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