Molecular Diagnostics Flashcards
7 cards from real Medical Laboratory Technician Exam practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Molecular Diagnostics flashcards as text
FISH (Fluorescence In Situ Hybridization) is primarily used to detect:
Answer: Chromosomal abnormalities and gene rearrangements
FISH uses fluorescently labeled DNA probes that hybridize to specific chromosomal regions, allowing visualization of chromosomal abnormalities, deletions, duplications, and translocations.
The BCR-ABL fusion gene detected by molecular methods is associated with which condition?
Answer: Chronic myelogenous leukemia (CML)
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.
DNA sequencing by the Sanger method uses which modified nucleotides to terminate chain elongation?
Answer: Dideoxyribonucleotides (ddNTPs)
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.
Which quality control measure is most important in a molecular diagnostics laboratory to prevent false-positive results?
Answer: Strict physical separation of pre- and post-amplification areas
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.
What is a molecular beacon probe in real-time PCR?
Answer: A hairpin-shaped probe with a fluorophore and quencher that fluoresces when hybridized
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.
Next-generation sequencing (NGS) differs from Sanger sequencing primarily in that NGS:
Answer: Sequences millions of DNA fragments simultaneously in a massively parallel manner
NGS platforms sequence millions of DNA fragments simultaneously through massively parallel processing, enabling whole-genome or whole-exome analysis at far greater throughput than Sanger sequencing.
A positive internal control in a PCR assay serves to:
Answer: Verify that PCR inhibitors in the specimen did not prevent amplification
An internal control (co-amplified with the target) confirms that the PCR reaction worked properly; if the internal control fails to amplify, it suggests inhibitors in the specimen caused a false-negative result.