the polymerase chain reaction and gel elctrophoresis

what is polymerase chain reaction and its purpose

• the polymerase chain reaction amplifies a sample of DNA by creating additional copies.

• amplifies DNA by making multiple identical copies. Used when there is an insufficient amount of DNA

• focuses on primers or restriction endonucleases

• after each cycle the amount of DNA present is doubled

step by step process of pcr

1. denaturation - DNA is heated to approx 90-95 to break the hydrogen bonds between the bases and seperate the strands, forming single stranded DNA

2. annealing - the single strand DNA is cooled to approx. 50-55 to allow the primers to bind to the complementary sequences on the single stranded DNA

3. elongation - the DNA is heated to 72 which allows taq polymerase to work optimally. Taq polymerase binds to the primer which acts as a starting point and begins synthesising a new complementary strand of DNA

4. repeat - the cycle is repeated multiple times for more copies of DNA

forward primer

• the forward primer will bind to the start codon at the 3’ end of the template strand. This causes taq polymerase to synthesis a new DNA strand in the same direction that RNA polymerase would function

the reverse primer

• the reverse primer which will bind to the stop codon at the 3’ end of the coding strand. this causes taq polymeraseto synthesis a new DNA strand in the reverse direction that RNA polymerase would function

what is gel electrophereisis

• gel electro is a technique that allows you to measure the size of DNA fragments. It seperates DNA fragments based on its molecular size.

application of pcr and gel electrophersis

• polymerase chain reaction and gel electrophoresis can be used in genetic testing and DNA profiling

DNA profiling

• we can compare DNA samples from a crime scene to DNA of suspects

• we can amplify DNA samples using pcr until there is a large amount of testable material

• DNA profiling can also discover how releated two people are. Mainly ised in parental testing when the identity of one parent is unknow.

• gel elctrophoresis is used