Question 1

Which of the following best describes the main advantage of using complementary DNA (cDNA) instead of genomic DNA when expressing a eukaryotic gene in bacteria?

Accepted Answer

cDNA contains only exons, so it lacks introns that bacteria cannot process.

Question 2

A researcher wants to clone a gene using a plasmid vector with an ampicillin resistance gene and the lacZ gene. After transformation and plating on agar containing ampicillin and X-gal, which colonies should the researcher select to ensure they contain the recombinant plasmid?

Accepted Answer

White colonies, because insertion of foreign DNA disrupts lacZ, preventing X-gal metabolism.

Question 3

Which restriction enzyme listed below would generate sticky ends compatible with the sequence $$5'	ext{AATT}\ 3'$$?

Accepted Answer

EcoRI

Question 4

In the process of Southern blotting, what is the primary purpose of using a labeled DNA probe?

Accepted Answer

To hybridize with and identify DNA fragments containing a specific gene of interest.

Question 5

A scientist uses PCR to amplify a segment of DNA. Which of the following best describes the role of primers in this process?

Accepted Answer

Primers provide a starting point for DNA polymerase to synthesize new DNA strands.

Question 6

Which of the following is a real-world application of the CRISPR-Cas9 system as described in the study materials?

Accepted Answer

Deleting PERV genes from pig genomes to make organs safer for human transplantation.

Question 7

A forensic scientist analyzes DNA from a crime scene and several suspects using gel electrophoresis. What is the basis for matching a suspect to the crime scene sample?

Accepted Answer

The pattern of DNA bands produced by restriction enzyme digestion and electrophoresis.

Question 8

Which of the following steps is essential for creating recombinant DNA using a plasmid vector and a gene of interest?

Accepted Answer

Cutting both the plasmid and the gene of interest with the same restriction enzyme.

Question 9

Why is site-directed mutagenesis a valuable tool in biotechnology?

Accepted Answer

It allows for the precise alteration of a specific DNA sequence to change a protein's function.

Question 10

Which of the following best explains why microarrays are useful for studying gene expression?

Accepted Answer

They allow simultaneous measurement of the expression levels of thousands of genes.

Question 11

A plasmid vector contains a gene for antibiotic resistance and a multiple cloning site within the lacZ gene. After transformation, which result indicates successful insertion of foreign DNA?

Accepted Answer

Colonies that are white on X-gal plates and resistant to the antibiotic.

Question 12

Which of the following is a function of DNA ligase in recombinant DNA technology?

Accepted Answer

It joins the sugar-phosphate backbones of DNA fragments to form a stable recombinant molecule.

Question 13

A scientist wants to identify bacterial colonies containing a specific gene using a radioactive probe. Which step ensures that only colonies with the gene of interest are detected?

Accepted Answer

Hybridization of the probe to complementary DNA sequences in the colonies.

Question 14

Which of the following best describes the role of restriction enzymes in the creation of recombinant DNA?

Accepted Answer

They cut DNA at specific sequences, generating compatible ends for ligation.

Question 15

In a blue-white screening experiment, what is the expected outcome if a bacterium takes up a plasmid without any foreign DNA inserted?

Accepted Answer

The colony will be blue because the lacZ gene is intact and can metabolize X-gal.

Question 16

Which of the following is a key reason why PCR is useful in forensic microbiology?

Accepted Answer

It can amplify trace amounts of DNA from a crime scene to detectable levels.

Question 17

A scientist is using real-time PCR to detect the presence of a pathogen in a sample. What feature of real-time PCR allows for quantification of DNA?

Accepted Answer

The use of fluorescent dyes that increase in intensity as DNA is amplified.

Question 18

Which of the following best explains why vectors are essential in recombinant DNA technology?

Accepted Answer

They carry foreign genes into host cells for replication and expression.

Question 19

A gene encoding a degradative enzyme is inserted into bacterial cells to clean up toxic waste. This is an example of which application of biotechnology?

Accepted Answer

Bioremediation

Question 20

Which of the following steps is NOT required for the production of a recombinant protein in bacteria?

Accepted Answer

Separating DNA fragments by gel electrophoresis after transformation.

Biotechnology and Recombinant DNA: Principles and Applications

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