Polymerase Chain reaction (PCR)
Polymerase Chain Reaction (PCR) is a scientific method that Stacy and the other scientists at the Sotka Lab use during their research. PCR is a method for creating multiple copies of a specific piece of DNA in a test tube. It is used in the lab for identifying genetic fingerprints (individual genes), which can distinguish between individuals of the same species using only their DNA. Stacy has used this method to identify the difference between male and female Gracilaria seaweeds.
PCR requires a few components in order to have a successful reaction:
PCR requires a few components in order to have a successful reaction:
- A DNA template containing the sequence of interest
- DNA polymerase- an enzyme used to create new strands of DNA
- Nucleotides- the basic building blocks of DNA
- A pair of DNA primers- these are short fragments of DNA that complement the DNA sequence of interest, they bind to the left and right end of the DNA sequence of interest
- Buffers containing magnesium ions- these make sure the chemical conditions are correct for the polymerase to work
What are the Steps in PRC Process?
PCR is a three-step, cyclic process where new strands of DNA can be created through rounds of denaturation, annealing and extensions using DNA polymerase.
This PCR cycles repeats between 30-40 times. After each cycle the amount of the DNA wanting to be duplicated is doubled.
- Denaturation: DNA is heated to around 95°C to separate the two strands of the double helix.
- Annealing: the temperature is lowered to about 50-60°C to allow the DNA primers to attach to the left and right ends of the separated strands.
- Extension: DNA polymerase synthesizes, or creates a new strand of DNA by adding nucleotides to one end of each DNA primer, making a copy of the region of the DNA between the two primers.
This PCR cycles repeats between 30-40 times. After each cycle the amount of the DNA wanting to be duplicated is doubled.
Thermocycler
The PCR reaction is carried out in a machine called a thermocycler. This machine heats and cools the reaction tubes to precise temperatures required for each step of the reaction to occur.
What is used with the PCR Product?
Gel electrophoresis machine
Up close of gel electrophoresis machine in use.