Question

What does PCR stand for? What is its principle? Name the three different steps involved in this reaction.

Answer 1

PCR stands for Polymerase Chain Reaction, a process used to amplify specific DNA segments. It consists of three key steps: denaturation, annealing, and extension, which are repeated in cycles to exponentially increase the quantity of the target DNA.

Step-by-step explanation:

PCR stands for Polymerase Chain Reaction. It is a technique used to amplify a segment of DNA of interest or produce many copies of a gene. This is useful for a variety of applications including genetic testing, research, and forensic analysis. The principle of PCR is based on the natural process of DNA replication, but it occurs in a controlled laboratory setting. The PCR cycle consists of three main steps:

1. Denaturation: DNA is heated to a high temperature (usually 94°C to 96°C) to separate the two strands of the DNA helix, resulting in single-stranded DNA molecules.
2. Annealing: The temperature is lowered (typically to around 55°C) to allow primers, which are short sequences of nucleotides that are complementary to the target DNA sequence, to bind to the single-stranded DNA.
3. Extension or DNA synthesis: The temperature is raised to the optimal working temperature for the enzyme Taq polymerase (usually about 72°C), which adds nucleotides to the primer, effectively building a new strand of DNA starting from the primer.

These steps are repeated for 20-40 cycles, which can be done quite rapidly in a DNA thermal cycler. With each cycle, the amount of DNA is doubled, leading to an exponential increase in the copy number of the target DNA segment.