Polymerase Chain Reaction (PCR) is a method of replication single or few copies of DNA to multitudes of copies. It is a very cheap and reliable way to replicate exact strands of DNA for scientists to use in research and experiments. PCR works by exposing the DNA strand to cycles of heating and cooling that cause the DNA melting and enzyme-driven replication. This can be used in the real world so scientists can study the same strand of DNA many times and in many different scenarios.
Gel Electrophoresis is a method used in laboratories that separates different strands of DNA RNA and proteins and then are pushed by an electric field through porous gel. The mixtures of the macromolecules are separated and the electrical charge causes them to move. This can be used when studying different mixtures of proteins DNA and RNA separately. In the real world it is used to estimate the size of DNA molecules.
DNA sequencing is the process of determining the order of the nucleotide bases in DNA. This can be used in the real world to determine the sequence of individual genes.