Question 1

Which of the following best describes recombinant DNA?

Accepted Answer

A DNA molecule formed by joining DNA from two different sources.

Question 2

What is the primary function of restriction enzymes in recombinant DNA technology?

Accepted Answer

To cleave DNA at specific sequences known as restriction sites.

Question 3

Which enzyme is responsible for joining together the sticky ends of DNA fragments during cloning?

Accepted Answer

DNA ligase

Question 4

A scientist wants to clone a gene into a plasmid. Which sequence of steps is most logical?

Accepted Answer

Extract plasmid DNA, cut with restriction enzymes, anneal gene fragment, ligate, transform bacteria.

Question 5

Why is a DNA polymerase from a thermophilic bacterium (such as Taq polymerase) used in PCR?

Accepted Answer

It can withstand the high temperatures required for DNA denaturation.

Question 6

Which of the following is NOT required for a polymerase chain reaction (PCR)?

Accepted Answer

DNA ligase

Question 7

If you start with one double-stranded DNA molecule and perform six cycles of PCR, how many double-stranded DNA molecules will you have?

Accepted Answer

$$2^6 = 64$

Question 8

During gel electrophoresis, why do DNA fragments move towards the positive electrode (anode)?

Accepted Answer

DNA is negatively charged and is attracted to the positive anode.

Question 9

Which of the following best explains why smaller DNA fragments migrate faster through an agarose gel during electrophoresis?

Accepted Answer

Smaller fragments experience less resistance moving through the gel matrix.

Question 10

A geneticist uses a radioactive DNA probe in a Southern blot. What does it mean if a band appears on the membrane?

Accepted Answer

The DNA fragment contains a sequence complementary to the probe.

Question 11

Which of the following is a key feature of short tandem repeats (STRs) that makes them useful for DNA fingerprinting?

Accepted Answer

The number of repeats is highly variable among individuals.

Question 12

Which of the following is NOT a component required for dideoxy (Sanger) sequencing?

Accepted Answer

RNA polymerase

Question 13

What is the role of dideoxynucleotides (ddNTPs) in Sanger sequencing?

Accepted Answer

They terminate DNA synthesis due to the lack of a free 3' OH group.

Question 14

Which of the following best describes the process of transformation in recombinant DNA technology?

Accepted Answer

The uptake of foreign DNA by a bacterial cell.

Question 15

A hospital uses DNA fingerprinting to confirm the identity of a newborn. Which result would confirm the baby is biologically related to the parents?

Accepted Answer

The baby's DNA bands match a combination of the mother's and father's bands.

Question 16

Which of the following is the correct order of steps in one cycle of the polymerase chain reaction (PCR)?

Accepted Answer

Denaturation, annealing, extension

Question 17

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

Accepted Answer

Production of human insulin in bacteria for diabetic patients.

Question 18

Which of the following statements about Southern blotting is correct?

Accepted Answer

It uses a labeled DNA probe to detect specific DNA sequences after gel electrophoresis.

Question 19

What is the main difference between PCR and DNA cloning?

Accepted Answer

PCR amplifies DNA in vitro (in a test tube), while cloning amplifies DNA in vivo (in living cells).

Question 20

Which of the following best describes the purpose of DNA fingerprinting?

Accepted Answer

To determine whether DNA samples from two locations are from the same individual.

Recombinant DNA Technology and DNA-Based Technologies: Study Notes

Study Guide - Practice Questions