Biology Q92 – NEET-UG 2025

Home Biology Molecular Basis of InheritanceQuestion #250

Polymerase chain reaction (PCR) amplifies DNA following the equation.

Clue 1 of 3: PCR Principle

Polymerase Chain Reaction (PCR) is a molecular biology technique used to make many copies of a specific DNA segment.

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Step 1: Understand PCR Amplification✦ Active

Polymerase Chain Reaction (PCR) is a technique designed to amplify a specific segment of DNA. The process involves multiple cycles, and in each cycle, the amount of target DNA is doubled.

Step 2: Determine the Amplification Pattern○ Expand

If we start with one DNA molecule (template), the amplification proceeds as follows:

- After 1 cycle: $1 \times 2 = 2$ DNA molecules

- After 2 cycles: $2 \times 2 = 4 = 2^{2}$ DNA molecules

- After 3 cycles: $4 \times 2 = 8 = 2^{3}$ DNA molecules

💡 Teacher's Secret Hint

This doubling effect is the core principle of PCR's efficiency.

Step 3: Formulate the Equation○ Expand

From the pattern observed, it is clear that after 'n' cycles, the number of DNA molecules will be $2^{n}$ times the initial number of molecules. Therefore, the equation representing DNA amplification in PCR is $2^{n}$ .

💡 Teacher's Secret Hint

The variable 'n' typically represents the number of PCR cycles.

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Biology Question 92 – NEET-UG 2025

Clue 1 of 3: PCR Principle

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