Which term best matches the description of a DNA copying technique that yields many copies of a target segment?

Which term best matches the description of a DNA copying technique that yields many copies of a target segment?

• A. Gel electrophoresis
• B. Restriction enzyme
• C. Polymerase chain reaction
• D. Karyotyping

Answer: (C)

The technique that copies a specific piece of DNA many times is PCR, because its purpose is to selectively amplify a target region from a DNA sample. It uses primers that flank the segment to be copied, a thermostable DNA polymerase, and repeating cycles of denaturation, primer annealing, and extension. Each cycle doubles the amount of the target DNA, so starting from a tiny amount you end up with millions of copies. This makes it possible to study or use a small original sample. Other options describe methods for different purposes: gel electrophoresis separates DNA by size rather than copying it; restriction enzymes cut DNA at specific sites rather than amplify it; karyotyping examines chromosome structure and number, not DNA amplification.

The technique that copies a specific piece of DNA many times is PCR, because its purpose is to selectively amplify a target region from a DNA sample. It uses primers that flank the segment to be copied, a thermostable DNA polymerase, and repeating cycles of denaturation, primer annealing, and extension. Each cycle doubles the amount of the target DNA, so starting from a tiny amount you end up with millions of copies. This makes it possible to study or use a small original sample. Other options describe methods for different purposes: gel electrophoresis separates DNA by size rather than copying it; restriction enzymes cut DNA at specific sites rather than amplify it; karyotyping examines chromosome structure and number, not DNA amplification.