Question 1

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

Accepted Answer

They cut DNA at specific sequences, generating sticky or blunt ends for gene insertion.

Question 2

A scientist wants to clone a gene into a plasmid vector. Which enzyme is required to join the gene of interest with the plasmid after both are cut with the same restriction enzyme?

Accepted Answer

DNA ligase

Question 3

Which of the following is a key feature of plasmids that makes them useful as cloning vectors in genetic engineering?

Accepted Answer

They contain antibiotic resistance genes for selection.

Question 4

During the selection of transformed bacteria, why is an antibiotic-containing medium used?

Accepted Answer

To select for bacteria that have taken up the plasmid with the antibiotic resistance gene.

Question 5

Which of the following best explains the principle of gel electrophoresis in DNA fingerprinting?

Accepted Answer

DNA fragments are separated based on their size, with smaller fragments migrating further toward the positive electrode.

Question 6

A patient with hemophilia requires regular injections of a protein produced by genetically engineered bacteria. Which protein is this, and what is the process used to produce it?

Accepted Answer

Blood-clotting factor VIII produced by recombinant DNA technology

Question 7

Which of the following statements about DNA probes is correct?

Accepted Answer

They are single-stranded DNA sequences labeled with a reporter molecule that hybridize to complementary DNA.

Question 8

In the Polymerase Chain Reaction (PCR), which step is responsible for the synthesis of new DNA strands?

Accepted Answer

Extension (elongation)

Question 9

A forensic scientist is analyzing DNA from a crime scene using pulse field gel electrophoresis (PFGE). What is the main advantage of PFGE over standard gel electrophoresis?

Accepted Answer

PFGE can separate very large DNA fragments, producing unique banding patterns for DNA fingerprinting.

Question 10

Which of the following equations correctly represents the exponential amplification of DNA during PCR, where $n$ is the number of cycles and $N_0$ is the initial number of DNA molecules?

Accepted Answer

$N = N_0 	imes 2^n$

Question 11

Which blotting technique would you use to detect specific RNA sequences in a sample?

Accepted Answer

Northern blot

Question 12

A researcher wants to confirm the presence of a recombinant plasmid in bacteria. Which of the following steps would be most effective?

Accepted Answer

Use a DNA probe specific for the inserted gene to hybridize with bacterial DNA.

Question 13

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

Accepted Answer

Production of insulin for diabetes treatment

Question 14

Why are sticky ends important in the process of gene cloning?

Accepted Answer

They allow complementary base pairing between vector and insert DNA, facilitating ligation.

Question 15

Which of the following best describes the function of a reporter molecule in a DNA probe?

Accepted Answer

It allows visualization or detection of hybridization events.

Question 16

A patient is treated with tissue plasminogen activator (tPA) produced by genetically engineered bacteria. What is the primary medical use of tPA?

Accepted Answer

Anticoagulant therapy for dissolving blood clots

Question 17

Which of the following steps is NOT part of the Polymerase Chain Reaction (PCR)?

Accepted Answer

Ligation

Question 18

In a Southern blot, what is the purpose of transferring DNA from the gel to a membrane?

Accepted Answer

To allow hybridization with a labeled probe for detection of specific sequences

Question 19

Which of the following is a critical difference between Southern and Northern blotting?

Accepted Answer

Southern blotting detects DNA, while Northern blotting detects RNA.

Question 20

A laboratory is investigating a multistate outbreak of Salmonella using DNA fingerprinting. Which combination of techniques is most likely used to generate unique banding patterns for each isolate?

Accepted Answer

Restriction endonuclease digestion and pulse field gel electrophoresis (PFGE)

Biotechnology and Recombinant DNA: Microbiology Study Guide

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