Polymerase Chain Reaction Essay

Polymerase Chain Reaction (PCR) is a laboratory technique used in molecular biology to generate a small section of DNA or genes, PCR uses primers to amplify specific genomic DNA sequences with the help of special enzymes, PCR process uses short sequences of DNA and primers and selects specific chromosomes of DNA for replication. (McPherson and Møller, 2009)

In addition, there are three main steps involve PCR process, first step of PCR is denaturing when DNA is heated to 90-95 degrees Celsius and double DNA strand is separated in to two single strands DNA, these single strand DNA will act as a template for the new strand DNA, because of the higher temperature the hydrogen bond which holds the complementary strands of DNA together is broken down at this step. (Wheeler et al., 2004)

The second stage in the PCR cycle is annealing, this step the temperature is cooled to 50-56 degrees Celsius so the DNA primers can attach to the template DNA by the hydrogen bonding. The final stage of PCR is extending stage when the temperature is raised to 72 degrees Celsius and a new strand of DNA is made by an enzyme called Taq DNA polymerase which is taken from the heat-loving bacteria Thermus aquaticus. This three-thermal process is repeated 20-40 times to produce many copies of the interested DNA sequences. (Hughes and Moody, 2007)

Furthermore, lines 4 (control GAPDH – HeLa Untreated), line 5 GAPDH – HeLa ATO 2 µM, and line 6 (GAPDH – HeLa ATO 5 µM) were all visible and shining on the original picture, however, the second picture line 5,6 and 7 are visible and shining whereas line 4 is absent, that is to say that the second experiment there was contamination because line 7 which is Non Template Control the band was present and this is due to either human error such as poor loading or reagent contamination of the reaction by the