Medical Laboratory Technician Exam Molecular Diagnostics 2

Question 1

FISH (Fluorescence In Situ Hybridization) is primarily used to detect:

Accepted Answer

Chromosomal abnormalities and gene rearrangements

Answer

FISH uses fluorescently labeled DNA probes that hybridize to specific chromosomal regions, allowing visualization of chromosomal abnormalities, deletions, duplications, and translocations.

Question 2

The BCR-ABL fusion gene detected by molecular methods is associated with which condition?

Accepted Answer

Chronic myelogenous leukemia (CML)

Answer

The BCR-ABL fusion gene results from the Philadelphia chromosome translocation t(9;22) and is the hallmark of CML, used for diagnosis and monitoring treatment response.

Question 3

DNA sequencing by the Sanger method uses which modified nucleotides to terminate chain elongation?

Accepted Answer

Dideoxyribonucleotides (ddNTPs)

Answer

Sanger sequencing incorporates dideoxynucleotides (ddNTPs), which lack a 3'-OH group, causing chain termination at specific bases, producing fragments of different lengths for sequence determination.

Question 4

Which quality control measure is most important in a molecular diagnostics laboratory to prevent false-positive results?

Accepted Answer

Strict physical separation of pre- and post-amplification areas

Answer

Physical separation of pre-amplification (specimen prep and PCR setup) from post-amplification (detection) areas prevents amplicon contamination, the primary cause of false-positive PCR results.

Question 5

What is a molecular beacon probe in real-time PCR?

Accepted Answer

A hairpin-shaped probe with a fluorophore and quencher that fluoresces when hybridized

Answer

Molecular beacons are hairpin-shaped oligonucleotides with a fluorophore at one end and a quencher at the other; when they hybridize to their target, the hairpin opens and fluorescence is emitted.

Medical Laboratory Technician Exam Practice Test

Medical Laboratory Technician Exam Practice Test

Medical Laboratory Technician Exam Molecular Diagnostics 2