PCR (Polymerase Chain Reaction):

PCR is a molecular biology technique to amplify a specific DNA segment.

Used in medical diagnostics, genetics, and forensics.

Involves replicating DNA in vitro, creating millions of copies of a target DNA.

DNA Synthesis:

DNA synthesis creates a complementary DNA strand to a template.

Essential for DNA replication and PCR.

DNA polymerase synthesizes a new DNA strand from nucleotide building blocks.

Requirements for PCR:

Key components: DNA template, primers, nucleotides (A, T, C, G), DNA polymerase (e.g., Taq polymerase).

Taq polymerase can withstand high PCR temperatures.

PCR Stages:

1. Denaturation: High temperature separates DNA strands.

2. Annealing: Lower temperature for primer binding.

3. Extension: Slight temperature increase; DNA synthesis from primers. Cycles repeated for exponential target DNA amplification.

Instrumentation: Thermal Cycler:

Automates precise temperature changes in PCR.

Repeated heating and cooling for denaturation, annealing, and extension.

Analysis of PCR Reaction:

DNA fragments analyzed post-PCR.

Techniques like agarose gel electrophoresis used.

Separates DNA fragments by size; confirms target presence and size.

Fluorescent dyes or DNA sequencing for detailed analysis.

Restriction Digestion and Ligation:

Restriction digestion cuts DNA at specific sites using enzymes.

Ligation joins DNA fragments with DNA ligase.

Used in molecular cloning to insert target DNA into vectors for various applications.