Which method is used to produce thousands of copies of a DNA segment?

The Polymerase Chain Reaction (PCR) is the method utilized to produce thousands to millions of copies of a specific DNA segment. This technique is pivotal in molecular biology because it enables researchers to amplify a specific DNA sequence, making it detectable and analyzable for various applications, such as genetic testing, forensic analysis, and research in biological sciences.

PCR involves a series of temperature changes that facilitate denaturation of the DNA, annealing of primers that are complementary to the target sequences, and extension by a DNA polymerase enzyme that synthesizes the new DNA strands. This cycle is repeated multiple times, exponentially increasing the amount of the targeted DNA segment.

In contrast, DNA hybridization refers to the process of forming a double-stranded nucleic acid molecule from two complementary strands. Serology is a diagnostic method that measures the presence of antibodies in the serum, while ELISA (Enzyme-Linked Immunosorbent Assay) is used to detect and quantify proteins, typically antibodies or antigens, in a sample. These methods do not focus on amplifying DNA segments like PCR does, thereby highlighting the unique capacity of PCR in handling DNA amplification.