The history of gel electrophoresis is quite complicated because so many people were researching similar topics in years of close proximity, but it seems the earliest development on electrophoresis began with Arne Tiselius in 1937. Tiselius’s findings first became known through his published paper, “A New Apparatus for Electrophoretic Analysis of Colloidal Mixtures,” where he described a principle called the “Tiselius apparatus” for moving boundary electrophoresis (“History”). Moving boundary electrophoresis is a technique which separated molecules in a free solution with a U-shaped tank with electrodes on opposite sides. This method was regularly used for a while until zone electrophoresis came into play. Zone electrophoresis worked by using filter paper or gels to separate molecules (“How was Gel Electrophoresis Developed?”). Zone electrophoresis was able to further separate compounds, unlike its predecessor, into DNA bands (“History”). Gel electrophoresis has continued to develop and improve to the method we now use today, which is the method we used in the lab. PCR was used many times in this lab, but that wouldn’t be possible without the work of Kary Mullis. In 1983, Mullis invented Polymerase Chain Reaction (PCR), which takes a strand of genetic material and enlarges it dramatically. He discovered it while attempting to put oligonucleotides in a higher demand (Mullis). Now research in other scientific studies have benefited from PCR. Taq polymerase and the thermal cycler have further developed PCR to what we use today. Because taq polymerase can endure such high temperatures it erased the need to intervene during the reaction. The thermal cycler was a program that controlled heating and cooling in a controlled manner. Both of these reduced the need for human disruption resulting in a more efficient and quicker process (“History of PCR”). Gel electrophoresis has many beneficial uses, such as, DNA fingerprinting, Southern blot, Western blot, and DNA sequencing (“How Was Gel”). When it comes to DNA fingerprinting, which it is most commonly used for, it can be used for forensics, paternity tests, the study of evolution, and testing genes for diseases (“Gel Electrophoresis,” Science Learning Hub). PCR is used for a variety of reasons. It is used for DNA sequencing by processing the early stages. Also, when it comes to infection and determining the pathogens it can identify the presence or absence of those genes. In forensics it is used to come up with DNA profiles from small fragments of DNA (“What is PCR”). Gel electrophoresis separates DNA through size and charge. The agarose gel must be prepared with wells formed by a comb at the negative charge of the machine. Once the DNA samples are dispensed in the wells, a buffer is poured over the gel to conduct electric current. There is a DNA ladder to provide standard known lengths of DNA fragments. When the gel box containing the agarose gel and DNA has been turned on, DNA fragments in the wells move from the negative end where they started to the positive charge at the other end. The smaller fragments of DNA move through the gel faster than the bigger fragments. The DNA samples are stained so the fragments can be seen in bands. After the gel has been running for a while it is turned off and the DNA bands can be seen. These bands are then compared to the DNA ladder (“Gel Electrophoresis,” Khan Academy). PCR amplifies a certain small segment of DNA. To set up the PCR there are five necessary components. One of the components is the DNA strand will be copied and another is a primer binds to either side of the desired copy DNA segment to begin the PCR reaction. Also, the DNA nucleotides that make up the DNA (A,T, G, C) necessary for the replication and the addition of new base pairs through taq polymerase are components in setting up PCR, as well as a buffer to control the reaction. PCR uses thermal cycling for heating and cooling which is a process in the PCR. The three main stages of PCR are denaturing, annealing, and extending. The repetition of this process multiplies the number of DNA. This whole process results in a multitude of DNA fragments which can now make DNA strands through the attachment of DNA polymerase (“What is PCR”).