What technique allows amplification of genes from a DNA sample?

• A. Gel Electrophoresis
• B. PCR
• C. Cloning
• D. Sequencing

Answer: (B)

Amplifying a target DNA sequence from a sample is best done with a method that uses primers to define the region and cycles of heating and cooling to build new copies. This process, called PCR, repeats denaturation, primer annealing, and extension over many cycles, so the target DNA grows exponentially in the reaction. The result is millions of copies of the specific gene or region you want, all in a test tube, without needing cells or cloning steps.

Gel electrophoresis, by contrast, separates DNA fragments by size after amplification or digestion, not the amplification itself. Cloning transfers the target DNA into a plasmid and grows it in living cells to produce copies, which can amplify but is slower and involves multiple steps. Sequencing determines the exact nucleotide order of DNA, not its quantity, so it doesn’t achieve amplification on its own.