Final answer:
The amount of DNA produced during real-time PCR is measured by fluorescence, which correlates with the quantity of DNA as it is synthesized in the PCR reaction.
Step-by-step explanation:
The amount of DNA produced during real-time PCR (Polymerase Chain Reaction) is measured by fluorescence. In real-time PCR, a DNA sample is first denatured by heating, and then a primer, DNA polymerase, and all four nucleotides are added to the mixture. Specialty nucleotides or probes labeled with a fluorescent dye are included in the reaction. As the PCR progresses and new DNA strands are synthesized, fluorescence increases in proportion to the amount of DNA produced. This fluorescence is measured in real-time, at each cycle of the PCR, allowing for the quantitation of DNA. Other methods like gel electrophoresis, UV spectroscopy, and mass spectrometry are used for different purposes in molecular biology but are not applicable to the real-time monitoring and quantitation of PCR products.