Choose the incorrect statement with respect to PCR reaction:

Options

A. It requires Taq polymerase.
B. It requires dNTP's.
C. It generates 2nmolecules after nnumber of cycles.
D. The optimum temperature for polymerization step is greater than or equal to `90^(@)C`.

Answer

To solve the question "Choose the incorrect statement with respect to PCR reaction," we will analyze each of the provided statements regarding the Polymerase Chain Reaction (PCR).

### Step-by-Step Solution:

1. **Understanding PCR**:
- PCR, or Polymerase Chain Reaction, is a technique used to amplify DNA. It involves repeated cycles of heating and cooling to denature the DNA, anneal primers, and extend the DNA strands.

2. **Evaluating the Statements**:
- **Statement 1**: "It requires the Taq polymerase."
- **Analysis**: This statement is true. Taq polymerase is a heat-stable enzyme derived from the bacterium Thermus aquaticus, and it is essential for the PCR process.

- **Statement 2**: "It requires dNTPs."
- **Analysis**: This statement is also true. PCR requires deoxynucleotide triphosphates (dNTPs) which are the building blocks for new DNA strands. The four types of dNTPs used are dATP, dTTP, dGTP, and dCTP.

- **Statement 3**: "It generates two N molecules after a number of cycles."
- **Analysis**: This statement is correct as well. After each cycle of PCR, the amount of DNA doubles, leading to a total of 2^n copies after n cycles.

- **Statement 4**: "The optimum temperature for the polymerization step is greater than or equal to 90 degrees Celsius."
- **Analysis**: This statement is incorrect. The optimum temperature for the polymerization step (where Taq polymerase synthesizes new DNA strands) is typically around 72 to 75 degrees Celsius, not 90 degrees Celsius.

3. **Conclusion**:
- The incorrect statement regarding the PCR reaction is the fourth option: "The optimum temperature for polymerization step is greater than or equal to 90 degrees Celsius."

### Final Answer:
The incorrect statement is: "The optimum temperature for polymerization step is greater than or equal to 90 degrees Celsius."

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