Which technique is commonly used for DNA amplification?

Polymerase Chain Reaction (PCR) is the technique widely used for DNA amplification because it enables the rapid and specific duplication of a particular segment of DNA. This method relies on thermal cycling, which involves repeated cycles of heating and cooling. During these cycles, the DNA strands are separated, and short nucleotide sequences known as primers bind to the target DNA regions. A special enzyme called DNA polymerase then synthesizes new DNA strands by extending these primers, effectively doubling the amount of DNA with each cycle. This exponential amplification allows researchers to create millions of copies of a specific DNA sequence from a very small initial sample, making it a fundamental tool in molecular biology, genetics, and biotechnology.

In contrast, gel electrophoresis is primarily used for separating DNA fragments based on size, DNA sequencing entails determining the exact order of nucleotides in a DNA molecule, and Southern blotting is a technique used for detecting specific DNA sequences within a complex mixture. While all of these techniques are important in molecular biology, they do not serve the primary purpose of amplifying DNA.