CHAPTER 12: Molecular Diagnostic Techniques

Question 1

What holds two single strands of DNA together in a double helix?
a. 2′ carbon of deoxyribose attached to a hydroxyl group
b. Hydrogen bonds between A and T and C and G
c. Ribose 3′ carbon hydroxyl attached to ribose 5′ carbon phosphate
d. Phosphorylation of nitrogen bases

Answer 1

b. Hydrogen bonds between A and T and C and G

Question 2

What is the complement to the following DNA sequence?

5′-GATCGATTCG-3′

a. 3′-CTAGCTAAGC-5′
b. 3′-CGAATCGATC-5′
c. 3′-GCTTAGCTAG-5′
d. 3′-GATCGATTCG-5′

Answer 2

a. 3′-CTAGCTAAGC-5′

Question 3

How are DNA and RNA different?
a. Only RNA contains uracil.
b. Only DNA contains cytosine.
c. DNA is usually single stranded.
d. DNA is less stable than RNA.

Answer 3

a. Only RNA contains uracil.

Question 4

What is the function of restriction endonucleases?
a. They splice short pieces of DNA together.
b. They cleave DNA at specific sites.
c. They make RNA copies of DNA.
d. They make DNA copies from RNA.

Answer 4

b. They cleave DNA at specific sites.

Question 5

What is the purpose of somatic hypermutation in genes that code for antibodies?
a. To increase diversity of the immunoglobulin repertoire
b. To prevent further antibody formation
c. To switch antibodies from IgM to IgG
d. To prevent further VDJ recombination

Answer 5

a. To increase diversity of the immunoglobulin repertoire

Question 6

What characteristic distinguishes restriction enzymes from one another?
a. Diverse binding and cutting sites
b. Ability to quickly digest DNA
c. RNA degradation capability
d. Ability of one enzyme to recognize several different binding sites

Answer 6

a. Diverse binding and cutting sites

Question 7

Which of the following is used in a Southern blot procedure?
a. A ligase joins two adjacent probes.
b. Radiolabeled nucleotides are used to synthesize DNA.
c. DNA is cleaved by enzymes and electrophoresed.
d. Many probes are placed on a small piece of glass.

Answer 7

c. DNA is cleaved by enzymes and electrophoresed.

Question 8

Which best describes the PCR?
a. Two probes are joined by a ligating enzyme.
b. RNA copies of the original DNA are made.
c. Extender probes are used to create a visible product.
d. Primers are used to make multiple DNA copies.

Answer 8

d. Primers are used to make multiple DNA copies.

Question 9

What takes place during in situ hybridization?
a. RNA polymerase copies messenger RNA.
b. Hybridization takes place in solution.
c. Nucleic acid probes react with intact cells in tissues.
d. Probes are protected from degradation if hybridized.

Answer 9

c. Nucleic acid probes react with intact cells in tissues.

Question 10

What determines the specificity for PCR?
a. Nucleotide mix ratios and concentrations
b. Mono- and divalent cation concentrations
c. Primers and their annealing temperature
d. DNA polymerase

Answer 10

c. Primers and their annealing temperature

Question 11

An antibody test for HIV within 3 months of exposure is negative. Does this guarantee a negative PCR test?
a. Yes, because if no antibodies are present, no virus is present.
b. No, PCR-detectable virus may be present before generation of detectable antibodies.
c. Yes, it has been 3 months since exposure.
d. No, but the PCR test will be less sensitive than the antibody test

Answer 11

b. No, PCR-detectable virus may be present before generation of detectable antibodies.

Question 12

How do PCR and qPCR differ?
a. In qPCR, the results can be seen at the end of each cycle.
b. SYBR Green is only used in PCR.
c. PCR is an isothermal process and qPCR is not.
d. Internal amplification controls are not necessary in qPCR.

Answer 12

a. In qPCR, the results can be seen at the end of each cycle.

Question 13

Which method is a signal amplification system?
a. bDNA
b. qPCR
c. PCR
d. Digital PCR

Answer 13

a. bDNA

Question 14

Which of the following amplifications is isothermal?
a. PCR
b. qPCR
c. NASBA
d. LCR

Answer 14

d. LCR

Question 15

Consider the following results for a qPCR test for the presence of herpes virus:

Sample Ct/Sample Ct/Amp Control
A 22.10 21.06
B 35.02 20.99

Which of the following statements is true?
a. The HSV viral load in sample A is greater than in sample B.
b. The HSV viral load in sample B is greater than in sample A.
c. The HSV viral load in sample A is about the same as in sample B.
d. The absolute number of viral particles in sample B is greater than in sample A.

Answer 15

d. The absolute number of viral particles in sample B is greater than in sample A.

Question 16

Which terminates chains when added to a DNA replication reaction?
a. dNTPs
b. ddNTPs
c. Sequencing primer
d. DNA polymerase

Answer 16

b. ddNTPs

Question 17

Which technique involves probe amplification rather than target amplification?
a. Southern blot
b. PCR
c. Transcription-mediated amplification
d. Ligase chain reaction

Answer 17

d. Ligase chain reaction

Question 18

How does next generation sequencing (NGS) technology differ from the original Sanger chain displacement sequencing?
a. NGS is more expensive to conduct than chain displacement sequencing.
b. NGS can sequence thousands of DNA pieces faster than Sanger sequencing.
c. Sanger sequencing involves ligation and NGS does not.
d. Only Sanger sequencing has direct clinical applications.

Answer 18

b. NGS can sequence thousands of DNA pieces faster than Sanger sequencing.

Question 19

Which of the following methods best describes a nucleic acid probe?
a. It attaches to double-stranded DNA.
b. It is used in transcription-mediated amplification.
c. It is used to detect specific single-stranded DNA sequences.
d. It plays a key role in DNA chain termination sequencing.

Answer 19

c. It is used to detect specific single-stranded DNA sequences.

Question 20

A hybridization reaction involves which of the following?
a. Separating DNA strands by heating
b. Binding of two complementary DNA strands
c. Increasing the number of DNA copies
d. Cleaving DNA into smaller segments

Answer 20

b. Binding of two complementary DNA strands

Question 21

What is the difference between a polymorphism and a mutation?
a. Mutations only affect A and T bases.
b. Mutations are more frequently present in a population.
c. Polymorphisms are more frequently present in a population.
d. Polymorphisms are easier to detect than mutations.

Answer 21

c. Polymorphisms are more frequently present in a population.