MCQ for PCR Mixture Preparation

Question 1: Which of the following is Not a component of PCR buffer?

NaCl
CORRECT! Sodium Chloride is not a component of PCR buffer. PCR buffer consists of KCl, Tris-HCl and MgCl₂.
KCl
INCORRECT! KCl is a component of PCR buffer.
Tris-HCl
INCORRECT! Tris-HCl is a component of PCR buffer.
MgCl₂
INCORRECT! MgCl₂ is a component of PCR buffer.

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Question 2: What is the sequence for PCR process?
I. Denaturation of the double-stranded DNA
II. DNA polymerase binds to template-primer hybrid
III. Annealing of primers with sequences that closely match with the template sequences, forming the primer-template hybrids

I, II, III
INCORRECT! The sequence is wrong. Please try again.
I, III, II
CORRECT! In a PCR cycle, 3 steps at different temperatures are involved. The first step involves denaturation of the double-stranded DNA, by disrupting the hydrogen bonds between complementary bases at high temperature, 94℃ for 15 seconds. After denatured into single-stranded DNA, annealing of primers with sequences that closely match with the template sequences occurs at 55℃ for 15 seconds, forming the primer-template hybrid. The DNA polymerase binds to this hybrid for DNA synthesis to take place. The DNA synthesis step of each cycle is carried out at 72℃ for 45 seconds.
II, I, III
INCORRECT! The sequence is wrong. Please try again.
II, III, I
INCORRECT! The sequence is wrong. Please try again.

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Question 3: Which of the following statements is true?

PCR requires the target DNA, one primer, all four deoxyribonucleotides and a thermostable DNA polymerase.
INCORRECT. Please try again.
PCR requires the target DNA, two primers, three deoxyribonucleotides and a thermostable DNA polymerase.
INCORRECT. Please try again.
The reaction requires the target DNA, two primers, one of four deoxyribonucleotides and a thermostable DNA polymerase
INCORRECT. Please try again.
The reaction requires the target DNA, two primers, all four deoxyribonucleotides and a thermostable DNA polymerase
CORRECT. The reaction requires the target DNA, two primers, all four deoxyribonucleotides and a thermostable DNA polymerase

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Question 4: Approximately, how many PCR cycles are needed for the original DNA to be amplified for further analysis?

2 times
INCORRECT. More cycles are required. Please try again.
20 times
CORRECT. The cycle of heating, cooling, and replication is usually repeated 20 to 30 times to amplify the DNA sufficiently for further analysis.
100-300 times
INCORRECT. Less cycles are required. Please try again.
1000-2000 times
INCORRECT. Less cycles are required. Please try again.

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Question 5: Taq polymerase is isolated from______.

Fungi
INCORRECT. Please try again.
Virus
INCORRECT. Please try again.
Bacteria
CORRECT. Taq polymerase is a heat-stable enzyme from Thermus aquaticus, a thermophilic bacterial species.
Plants
INCORRECT. Please try again.

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Finish!