Question 1

Which of the following best describes the function of the Dicer enzyme in RNA interference pathways?

Accepted Answer

It cleaves double-stranded RNA into small interfering RNAs (siRNAs) and microRNAs (miRNAs).

Question 2

A researcher wants to overexpress a human insulin gene in mammalian cells. Which plasmid feature is essential for driving high levels of transgene expression?

Accepted Answer

A constitutive or strong mammalian promoter such as the CMV promoter

Question 3

In the pBR322 plasmid, insertion of foreign DNA into the ampicillin resistance gene will result in which of the following outcomes?

Accepted Answer

Bacteria containing the recombinant plasmid will be sensitive to ampicillin but resistant to tetracycline.

Question 4

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

Accepted Answer

It divides rapidly and is easy to genetically manipulate.

Question 5

A scientist uses electroporation to introduce a plasmid into bacterial cells. What is the main principle behind this technique?

Accepted Answer

A high-voltage electric pulse temporarily disrupts the cell membrane, allowing DNA to enter.

Question 6

Which of the following is a key difference between a genomic library and a cDNA library?

Accepted Answer

A cDNA library is generated from mRNA and represents only expressed genes, while a genomic library contains all DNA sequences, including non-coding regions.

Question 7

In the context of gene therapy for cystic fibrosis, which of the following best describes the therapeutic strategy?

Accepted Answer

Delivering a functional copy of the CFTR gene to patient cells using a viral vector

Question 8

Which of the following statements about transgenic mice generated by pronuclear injection is correct?

Accepted Answer

The transgene is randomly integrated into the genome, often as tandem repeats.

Question 9

A knockout mouse is generated using homologous recombination in embryonic stem cells. What is the main advantage of this approach compared to pronuclear injection?

Accepted Answer

It allows for targeted disruption of a specific gene via homologous recombination.

Question 10

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 11

A researcher wants to create a mouse model in which a gene is knocked out only in the liver. Which of the following strategies should be used?

Accepted Answer

Cross a mouse with a loxP-flanked gene (floxed) with a mouse expressing Cre recombinase under the control of a liver-specific promoter.

Question 12

Which of the following is a key feature of inducible Cre-loxP systems in mouse genetics?

Accepted Answer

Cre recombinase activity is controlled by administration of an exogenous ligand such as tamoxifen.

Question 13

Which of the following best explains the difference between a knockout and a knock-in mouse?

Accepted Answer

A knockout mouse has a gene deleted or disrupted, while a knock-in mouse has a specific gene or mutation inserted at a targeted locus.

Question 14

A scientist is using RNA interference to study gene function in cultured cells. Which of the following is the most likely outcome of introducing siRNA targeting a specific mRNA?

Accepted Answer

The targeted mRNA will be degraded, leading to reduced protein expression.

Question 15

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

Accepted Answer

$$2n \rightarrow n$$

Question 16

In a Southern blot analysis to identify transgenic mice, which result would indicate a successful integration of the transgene?

Accepted Answer

A DNA band corresponding to the transgene in addition to or instead of the wild-type band

Question 17

A mouse with a knockout of the leptin gene exhibits which of the following phenotypes?

Accepted Answer

Increased hunger and obesity due to lack of leptin signaling

Question 18

Which of the following best describes the role of the neomycin resistance (NeoR) cassette in gene targeting experiments?

Accepted Answer

It allows for positive selection of cells that have incorporated the targeting vector via homologous recombination.

Question 19

A scientist is designing a PCR primer to detect a transgene in mouse genomic DNA. Which of the following is the most important consideration?

Accepted Answer

The primer should specifically anneal to a unique sequence within the transgene.

Recombinant DNA Technology and Transgenic Models: Genetics Study Guide

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