Steps of PCR in sequence are?
**Core Concept**
Polymerase Chain Reaction (PCR) is a molecular biology technique used to amplify specific DNA sequences. It involves three main steps: denaturation, annealing, and extension, which are repeated multiple times to achieve exponential amplification of the target DNA.
**Why the Correct Answer is Right**
The correct answer sequence is as follows: Denaturation, Annealing, Extension. Denaturation involves heating the DNA to separate the double strands into single strands, making the target sequence accessible to primers. Annealing involves cooling the DNA to allow the primers to bind to the target sequence. Extension involves the action of DNA polymerase, which synthesizes new DNA strands complementary to the template strands. This process is repeated multiple times, with each cycle consisting of denaturation, annealing, and extension.
**Why Each Wrong Option is Incorrect**
* **Option A:** This sequence is incorrect because denaturation should occur before annealing, not after.
* **Option B:** This sequence is incorrect because extension should occur after annealing, not before.
* **Option C:** This sequence is incorrect because the correct sequence is denaturation, annealing, extension, not the reverse.
**Clinical Pearl / High-Yield Fact**
It's essential to remember the acronym "D-A-E" to recall the correct sequence of PCR steps: Denaturation, Annealing, Extension.
**Correct Answer: D. Denaturation, Annealing, Extension.**