Medical Laboratory Technician Exam Molecular Diagnostics

Question 1

Which technique is used to amplify specific DNA sequences in molecular diagnostics?

Accepted Answer

Polymerase chain reaction (PCR)

Answer

PCR (polymerase chain reaction) uses thermal cycling with DNA polymerase to exponentially amplify specific DNA sequences.

Question 2

What is the purpose of the denaturation step in PCR?

Accepted Answer

To separate double-stranded DNA into single strands

Answer

Denaturation (typically at 94-98°C) breaks the hydrogen bonds between complementary base pairs, separating double-stranded DNA into single strands so primers can bind.

Question 3

Which enzyme is essential for the PCR amplification process?

Accepted Answer

Taq polymerase

Answer

Taq polymerase, derived from Thermus aquaticus, is a heat-stable DNA polymerase that can withstand the high temperatures used in PCR cycling.

Question 4

In real-time PCR (qPCR), fluorescence is measured to:

Accepted Answer

Quantify the amount of target DNA during amplification

Answer

In real-time PCR, fluorescent dyes or probes generate a signal proportional to the amount of amplified DNA, allowing quantification during each cycle.

Question 5

Which molecular technique is used to detect RNA viruses such as HIV or SARS-CoV-2?

Accepted Answer

Reverse transcriptase PCR (RT-PCR)

Answer

RT-PCR first converts RNA into complementary DNA (cDNA) using reverse transcriptase before PCR amplification, making it suitable for RNA virus detection.

Medical Laboratory Technician Exam Practice Test

Medical Laboratory Technician Exam Practice Test

Medical Laboratory Technician Exam Molecular Diagnostics