PCR Review Exam Updated ACTUAL
QUESTIONS AND CORRECT ANSWERS
What are the three main steps of PCR and what happens in each? - CORRECT
ANSWER "Denaturation (DNA strands separate), annealing (primers bind to target),
extension (DNA polymerase synthesizes new DNA)."
What is the function of primers in PCR? - CORRECT ANSWER They provide a
starting point for DNA polymerase and determine the specificity of amplification.
What role does Taq polymerase play in PCR? - CORRECT ANSWER "It synthesizes
new DNA strands and is heat-stable, allowing it to function during repeated high-temperature
cycles."
Why is Mg²⁺ important in PCR reactions? - CORRECT ANSWER It acts as a cofactor
for DNA polymerase; incorrect concentrations can reduce yield or increase nonspecific
amplification.
What is a positive control in PCR and why is it important? - CORRECT ANSWER A
sample known to contain the target sequence; confirms the PCR reaction is working properly.
What is a negative or no-template control (NTC)? - CORRECT ANSWER A reaction
without DNA template; used to detect contamination.
What is the difference between conventional PCR and qPCR? - CORRECT
ANSWER "Conventional PCR detects DNA at the end of the reaction, while qPCR
measures amplification in real time using fluorescence."
What does a high Ct value in qPCR indicate? - CORRECT ANSWER A low amount of
starting target DNA.
QUESTIONS AND CORRECT ANSWERS
What are the three main steps of PCR and what happens in each? - CORRECT
ANSWER "Denaturation (DNA strands separate), annealing (primers bind to target),
extension (DNA polymerase synthesizes new DNA)."
What is the function of primers in PCR? - CORRECT ANSWER They provide a
starting point for DNA polymerase and determine the specificity of amplification.
What role does Taq polymerase play in PCR? - CORRECT ANSWER "It synthesizes
new DNA strands and is heat-stable, allowing it to function during repeated high-temperature
cycles."
Why is Mg²⁺ important in PCR reactions? - CORRECT ANSWER It acts as a cofactor
for DNA polymerase; incorrect concentrations can reduce yield or increase nonspecific
amplification.
What is a positive control in PCR and why is it important? - CORRECT ANSWER A
sample known to contain the target sequence; confirms the PCR reaction is working properly.
What is a negative or no-template control (NTC)? - CORRECT ANSWER A reaction
without DNA template; used to detect contamination.
What is the difference between conventional PCR and qPCR? - CORRECT
ANSWER "Conventional PCR detects DNA at the end of the reaction, while qPCR
measures amplification in real time using fluorescence."
What does a high Ct value in qPCR indicate? - CORRECT ANSWER A low amount of
starting target DNA.
