Polymerase chain reaction

Question 1

What is PCR used for?

Answer 1

prenatal diagnosis
detection of mutated oncogenes
diagnosis of infections
also extensively used in forensics

Question 2

Describe how PCR takes place

Answer 2

sample of DNA is added to the test tube along with two DNA primers
a thermostable DNA polymerase (Taq) is added

mixture is heated to almost boiling point causing denaturing (uncoiling) of DNA
mixture is then allowed to cool and primers bind
Taq polymerase replicates DNA as it is reheated to high temp

amount of DNA doubles with each cycle

Question 3

What is reverse transcriptase PCR used for?

Answer 3

used to amplify RNA
RNA is converted to DNA by reverse transcriptase
gene expression in the form of mRNA (rather than the actually DNA sequence) can therefore be analyzed