In order to analyze a DNA sample a laboratory scientist first needs to find a specific sequence within it. This requires DNA replication, which essentially isolates a specific DNA sequence amongst the thousands of others in the human genome and duplicates it. Before the early 1980s this process would take hours and even days, but in 1983 a genetic scientist called Kate Mullins developed PCR; a process that would dramatically improve the DNA analysis process forever.
PCR, also known as Polymerase Chain Reaction, soon became the most widely and commonly used DNA replication technique in the world. Within ten years of its development, founder Kate Mullins had been awarded a chemistry Nobel prize for making the process of DNA replication so much faster, and possible with such a small sample of DNA. The process can now be carried out with only a single strand of hair, or the tiny amount of cells collected on a cheek swab. The DNA sample can also come from anywhere in the body, meaning that all physical evidence found at a crime scene, be it a spot of blood or just one eyelash, is incredibly useful.
Perhaps the most prolific use of the polymerase chain reaction technique today is in paternity testing. If someone wants to know if they are the father of a particular child, then obtaining a buccal swab from both individuals is all that is needed. These samples are sent to a laboratory where they undergo PCR, followed by electrophoresis to amplify and dye the data each sample gives. Laboratory professionals then analyze this data and compare the two genetic profiles. If they share particular similarities then it can be confirmed that the two are father and child. Maternal testing, sibling testing and testing for a grand-parental relationship is also possible using PCR.
Much of the world of forensics today relies heavily on the efficiency of DNA testing to keep court cases and investigations running smoothly. Without the development of PCR in 1983 DNA testing would take well over one week to provide results, as opposed to the few days that we expect now.