Question

The variation in temperatures in the three steps of PCR cycle is ___________, ___________ and ___________ respectively.

• A. \(95\text\degree C, 62\text\degree C and \ 82\text\degree C\)
• B. \(97\text\degree C, 60\text\degree C and \ 92\text\degree C\)
• C. \(100\text\degree C, 75\text\degree C and \ 88\text\degree C\)
• D. \(91\text\degree C, 55\text\degree C and \ 72\text\degree C \)

Hint:

Remember PCR temperatures as: Denaturation ~95\textdegree C, Annealing ~55\textdegree C, Extension ~72\textdegree C.

Answer 1

The Correct Option is D

Step 1: Understanding PCR steps. 
Polymerase Chain Reaction (PCR) consists of three repeated steps: denaturation, annealing, and extension. Each step requires a specific temperature range for optimal functioning. 
Step 2: Temperature requirements of each step. 
Denaturation occurs at about \(90–95\text\degree C\) to separate the DNA strands. 
Annealing occurs at around \(50–60\text\degree C\) to allow primers to bind to the template DNA. 
Extension occurs at \(72\text\degree C\), the optimum temperature for Taq DNA polymerase to synthesize new DNA strands. 
Step 3: Analysis of options. 
Only option (D) correctly represents the standard temperatures for denaturation, annealing, and extension respectively. 
Step 4: Conclusion. 
The correct temperature sequence in PCR is \(91\text\degree C, 55\text\degree C and \ 72\text\degree C. \)