Question 1

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

Accepted Answer

They make double-stranded cuts at specific DNA sequences, allowing for precise DNA manipulation.

Question 2

A researcher wants to clone a gene into a plasmid vector using EcoRI. Which feature of EcoRI is most critical for this process?

Accepted Answer

EcoRI recognizes a palindromic sequence and creates sticky ends, facilitating the insertion of foreign DNA.

Question 3

Which of the following equations correctly predicts the average fragment size produced by a restriction enzyme that recognizes a 6-base pair sequence in random DNA?

Accepted Answer

$$4^6 = 4096$ base pairs

Question 4

In blue/white screening using the pUC18 plasmid, what does the appearance of white colonies on X-gal plates indicate?

Accepted Answer

The bacteria contain a recombinant plasmid with an inserted gene disrupting lacZ.

Question 5

Which of the following is a major advantage of using a shuttle vector in yeast genetic engineering?

Accepted Answer

It can replicate and express genes in both yeast and E. coli, facilitating DNA manipulation and transfer.

Question 6

A scientist is constructing a genomic DNA library. Which of the following steps is unique to the creation of a cDNA library?

Accepted Answer

Reverse transcription of mRNA to synthesize complementary DNA.

Question 7

Which of the following best explains why the Flavr Savr tomato was genetically engineered?

Accepted Answer

To prevent the production of polygalacturonase, slowing fruit softening and spoilage.

Question 8

Golden Rice was engineered to address which global health issue, and what genes were introduced to achieve this?

Accepted Answer

Vitamin A deficiency; a bacterial gene and a daffodil (later maize) gene for β-carotene synthesis.

Question 9

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

Accepted Answer

It uses a protein and a guide RNA to introduce double-stranded breaks at specific DNA sequences.

Question 10

A gene drive using CRISPR is designed to spread a genetic trait through a population. Which mechanism ensures its rapid spread?

Accepted Answer

The gene drive copies itself onto the homologous chromosome, ensuring nearly all offspring inherit the trait.

Question 11

Which of the following is a major challenge in gene therapy for human diseases?

Accepted Answer

Ensuring the transgene is delivered to the correct cells without disrupting essential genes.

Question 12

Which of the following best describes the difference between genomic and cDNA libraries?

Accepted Answer

Genomic libraries represent the entire genome, while cDNA libraries represent only expressed genes (mRNA).

Question 13

Which of the following is a correct sequence of steps for creating a recombinant plasmid containing a gene of interest?

Accepted Answer

Isolation of gene and plasmid, restriction digestion, ligation, transformation, selection, screening.

Question 14

Why are transgenic E. coli used to produce human insulin considered a major milestone in biotechnology?

Accepted Answer

They enabled large-scale, cost-effective production of human insulin for medical use.

Question 15

Which of the following best explains why animal cloning is more challenging than plant cloning?

Accepted Answer

Animal cells are not totipotent, so cloning requires manipulation of gametes or early embryos.

Question 16

A researcher uses CRISPR-Cas9 to introduce a double-stranded break in a gene. If no homologous template is provided, which DNA repair mechanism is most likely to occur, and what is a possible outcome?

Accepted Answer

Non-homologous end joining (NHEJ); introduction of random mutations that may disable the gene.

Question 17

Which of the following is a real-world application of gene drives using CRISPR technology?

Accepted Answer

Eradicating disease vectors such as malaria-carrying mosquitoes by spreading a trait that biases sex ratios.

Question 18

Which of the following best describes the role of DNA ligase in molecular cloning?

Accepted Answer

It catalyzes the formation of phosphodiester bonds between adjacent nucleotides, sealing nicks in the DNA backbone.

Recombinant DNA Technology and Its Applications: Study Notes

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