Deck 13: Molecular Diagnostics

Question 1

____________ forms the basis for almost all types of DNA detection methods.

A)denaturation
B)hybridization
C)restriction fragment length polymorphism (RFLP)
D)amplification

Answer 1

hybridization

Question 2

What is the current detection limit for test systems available to measure HIV RNA viral loads?

A)40 to 50 copies/mL
B)500 to 750 copies/mL
C)10,000 copies/mL
D)100,000 copies/mL

Answer 2

40 to 50 copies/mL

Question 3

The mutation-detection technique designed to amplify only one of the alleles present at the locus of interest by the use of primers that are substantially mismatched at one allele but have sufficient complementarity to anneal to and amplify the other allele is known as:

A)PCR-mediated site-directed mutagenesis (PSM) technique
B)amplification refractory mutation system (ARMS) technique
C)allele-specific oligonucleotide hybridization (ASO or dot blot) technique
D)reverse dot blot technique

Answer 3

amplification refractory mutation system (ARMS) technique

Question 4

In denaturing high-performance liquid chromatography, what is the purpose of adding triethylammonium acetate (TEAA) to the mobile phase?

A)to adjust the pH of the mobile phase to that appropriate for DNA analysis
B)to denature DNA during chromatography
C)to serve as an ion-pairing reagent
D)to adjust the chromatographic environment to the appropriate ionic strength

Question 5

Which of the following statements are true regarding HIV viral-load testing results?
1)Viral RNA is detectable in plasma about 2 weeks after the infection is established.
2)HIV viral-load levels can serve as a predictor of the progression time to AIDS.
3)In HIV infections, treatment goals are to maintain HIV viral-load levels at less than 10,000 copies/mL.

A)1, 2, 3
B)1, 2
C)2, 3
D)1, 3

Question 6

Select the order of processes in the Southern blot transfer technique.(Steps are listed in order performed, with the first step listed first.)

A)RNA isolation, electrophoresis under denaturing conditions, transfer, hybridization, detection
B)electrophoresis under denaturing conditions, transfer, RNA isolation, hybridization, detection
C)DNA isolation, restriction enzyme digestion, electrophoresis, denaturation, transfer, hybridization, detection
D)electrophoresis, denaturation, transfer, DNA isolation, restriction enzyme digestion, hybridization, detection

Question 7

Of the viral load assay systems currently available, which is the only FDA-approved system for the diagnosis of HIV infection?

A)Procleix HIV-1/HCV Assay
B)APTIMA HIV-1 RNA Qualitative Test
C)Abbott RealTime HIV-1 Viral Load Test
D)NucliSens HIV-1 QT

Question 8

Select the order of processes in the polymerase chain reaction cycle.(Steps are listed in the order performed with the first step listed first.)

A)denaturation, primer annealing, polymerase extension
B)primer annealing, denaturation, polymerase extension
C)polymerase extension, denaturation, primer annealing
D)polymerase extension, primer annealing, denaturation

Question 9

The real-time PCR technique that utilizes two fluorophores where the emission spectrum of one fluorophore overlaps the excitation spectrum of the second fluorophore is known as the:

A)TaqMan technique
B)fluorescence resonance energy transfer (FRET) technique
C)multiplex ligation probe amplification (MLPA) technique
D)heteroduplexing technique

Question 10

The most commonly used DNA polymerase is Taq polymerase, which has an optimal activity at ______ but can survive short periods of exposure to temperatures up to ______.

A)60°C, 72°C
B)60°C, 95°C
C)72°C, 95°C
D)72°C, 112°C

Question 11

Fluorescent probes that hybridize to PCR products during amplification change fluorescence by two mechanisms._____ probes change fluorescence by breaking covalent bonds between the probes, and _____ probes change fluorescence based on the proximity of the two probes.Melting curve profiles are only possible with _____ probes.

A)TaqMan, FRET, TaqMan
B)TaqMan, FRET, FRET
C)FRET, TaqMan, TaqMan
D)FRET, TaqMan, FRET

Question 12

Single-stranded conformational polymorphism analysis (SSCP) and heteroduplex analysis are two mutation scanning techniques that have which of the following in common?

A)Conformational changes resulting from mutations are detected by electrophoretic differences.
B)Conformational changes resulting from mutations are detected by changes in fluorescence intensity.
C)The presence of mutations is detected in these techniques by scanning UV/visible spectrophotometry identifying changes in wavelengths of maximum absorbance.
D)The presence of mutations is detected in these techniques by variations in melting temperature.

Question 13

Which of the following statements are correct regarding mutations?
1)Mutations are changes in the base sequence in DNA and may include insertion, deletion, or replacement.
2)Mutations may result in no effect on protein expression or functional activity.
3)Mutations may result in partial or total loss of protein function.
4)Mutations always result in disease.

A)1, 2, 3
B)1, 3, 4
C)1, 2
D)3, 4

Question 14

A ______ mutation is one that is present in all cells of the body and is passed from generation to generation.A ______ mutation is one that arises in tissue cells generally as a result of an environmental insult or DNA replication error.The majority of cancers result from ______ mutations.

A)germline, somatic, germline
B)germline, somatic, somatic
C)somatic, germline, germline
D)somatic germline, somatic

Question 15

The most common method for visualizing DNA following electrophoretic size separation involves the use of ______, which is fluorescent _____.

A)silver nitrate, prior to binding to the DNA double helix
B)ethidium bromide, prior to binding to the DNA double helix
C)silver nitrate, after binding to the DNA double helix
D)ethidium bromide, after binding to the DNA double helix

Question 16

The mutation-detection technique that incorporates a set of immobilized DNA probes for different sequence variants to which PCR amplified DNA is added is known as:

A)PCR-mediated site-directed mutagenesis (PSM) technique
B)amplification refractory mutation system (ARMS) technique
C)allele-specific oligonucleotide hybridization (ASO or dot blot) technique
D)reverse dot blot technique

Question 17

The assumption underlying real-time PCR is that the amount of fluorescence in the reaction chamber is:

A)directly proportional to the amount of amplicon present in the PCR vessel
B)inversely proportional to the amount of amplicon present in the PCR vessel
C)directly proportional to the amount of target template present at the beginning of the reaction
D)both a and c