During DNA fingerprinting, which process is used to make billions of copies of a specific DNA segment?

The correct answer is indeed Polymerase Chain Reaction (PCR) because it is a technique specifically designed to amplify a particular segment of DNA, resulting in billions of copies of that segment. This amplification is crucial for DNA fingerprinting, as it allows for sufficient quantities of DNA to be analyzed for identifying genetic differences among individuals.

PCR involves a series of temperature changes that facilitate the denaturation of DNA, annealing of primers to target sequences, and extension by DNA polymerase, which synthesizes new strands of DNA. This cycle is repeated multiple times, leading to exponential growth of the desired DNA segment.

In contrast, gel electrophoresis is a technique used for separating DNA fragments based on size, not for amplifying them. Restriction enzyme digestion cuts DNA at specific sequences; while this is useful for preparing DNA samples or analyzing sizes of fragments after PCR, it does not amplify DNA. DNA sequencing determines the exact order of nucleotides in a DNA molecule but does not involve amplification. Thus, PCR is the essential method for producing ample amounts of specific DNA for fingerprinting and other genetic analyses.