Which method amplifies DNA sequences using a heat-stable enzyme and can generate billions of copies?

Which method amplifies DNA sequences using a heat-stable enzyme and can generate billions of copies?

• A. Genome
• B. Polymerase chain reaction (PCR)
• C. ABO blood type system
• D. Recessive

Answer: (B)

PCR, or polymerase chain reaction, is the method that amplifies DNA sequences using a heat-stable enzyme and can generate billions of copies. The trick is using a DNA polymerase that remains active after heating, so the reaction can go through repeated cycles of heating and cooling. First, the DNA is heated to around 95°C to separate the strands (denaturation). Then the temperature is lowered to allow short DNA primers to bind to the target sequence (annealing). Finally, the polymerase extends from the primers to build new DNA strands (extension), using nucleotides to copy the target region. Each cycle doubles the amount of DNA, so after roughly 30–40 cycles you can reach billions of copies from a tiny starting sample. This capability underpins many applications, from medical diagnostics to forensics. The other options refer to a whole genome, a blood type system, or a recessive trait, none of which describe the DNA amplification technique.

PCR, or polymerase chain reaction, is the method that amplifies DNA sequences using a heat-stable enzyme and can generate billions of copies. The trick is using a DNA polymerase that remains active after heating, so the reaction can go through repeated cycles of heating and cooling. First, the DNA is heated to around 95°C to separate the strands (denaturation). Then the temperature is lowered to allow short DNA primers to bind to the target sequence (annealing). Finally, the polymerase extends from the primers to build new DNA strands (extension), using nucleotides to copy the target region. Each cycle doubles the amount of DNA, so after roughly 30–40 cycles you can reach billions of copies from a tiny starting sample. This capability underpins many applications, from medical diagnostics to forensics. The other options refer to a whole genome, a blood type system, or a recessive trait, none of which describe the DNA amplification technique.