Medical Laboratory Technician Exam Molecular Diagnostics 3

Question 1

Restriction fragment length polymorphism (RFLP) analysis uses which enzymes?

Accepted Answer

Restriction endonucleases

Answer

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.

Question 2

Which molecular method is used to detect MRSA (methicillin-resistant Staphylococcus aureus)?

Accepted Answer

Detection of the mecA gene by PCR

Answer

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.

Question 3

What is the primary purpose of a melting curve analysis in real-time PCR?

Accepted Answer

To confirm amplicon identity and detect mutations or SNPs

Answer

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.

Question 4

Gel electrophoresis separates DNA fragments based on:

Accepted Answer

Fragment size (number of base pairs)

Answer

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).

Question 5

Which of the following is a common inhibitor of PCR found in blood specimens?

Accepted Answer

Heparin

Answer

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.

Medical Laboratory Technician Exam Practice Test

Medical Laboratory Technician Exam Practice Test

Medical Laboratory Technician Exam Molecular Diagnostics 3