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
Restriction fragment length polymorphism (RFLP) analysis uses which enzymes?
Answer: Restriction endonucleases
RFLP analysis uses restriction endonucleases that cut DNA at specific recognition sequences, creating fragments of different lengths that can be used for genetic typing or identification.
Which molecular method is used to detect MRSA (methicillin-resistant Staphylococcus aureus)?
Answer: Detection of the mecA gene by PCR
MRSA is detected molecularly by identifying the mecA gene (or mecC), which encodes an altered penicillin-binding protein (PBP2a) that confers resistance to methicillin and related beta-lactam antibiotics.
What is the primary purpose of a melting curve analysis in real-time PCR?
Answer: To confirm amplicon identity and detect mutations or SNPs
Melting curve analysis monitors fluorescence as the PCR product is slowly heated; the melting temperature (Tm) is characteristic of specific amplicons and can identify mutations, SNPs, or nonspecific products.
Gel electrophoresis separates DNA fragments based on:
Answer: Fragment size (number of base pairs)
In agarose gel electrophoresis, DNA fragments migrate through the gel matrix under an electric field; smaller fragments migrate faster and farther, separating fragments by size (base pairs).
Which of the following is a common inhibitor of PCR found in blood specimens?
Answer: Heparin
Heparin is a potent PCR inhibitor because it binds to DNA polymerase and prevents it from functioning; EDTA-anticoagulated blood is preferred for molecular testing.
Loop-mediated isothermal amplification (LAMP) differs from PCR in that LAMP:
Answer: Amplifies DNA at a constant temperature without thermal cycling
LAMP uses strand displacement DNA synthesis at a constant temperature (60-65°C) with a set of 4-6 primers, making it suitable for point-of-care testing without specialized thermocyclers.
Which technique uses labeled probes hybridized to target nucleic acid on a membrane to detect gene expression patterns?
Answer: Northern blot
Northern blotting transfers RNA to a membrane and hybridizes it with labeled probes to detect and quantify specific RNA (mRNA) sequences, providing information about gene expression levels.