3.6 - Amplifying DNA 🧬 Flashcards
what is polymerase chain reaction (PCR)?
a cyclical reaction where DNA polymerase is used to copy a DNA template
what components are required for PCR?
- DNA that will be copied (the template DNA)
- DNA polymerase (the enzyme)
- a buffer solution that contains salt and other chemicals that help the polymerase to function (called cofactors)
- a supply of the four nucleotides to build the new DNA molecules two primers
what is the first step in PCR?
Denaturation: the double-stranded DNA is heated to 95’c. This breaks the hydrogen bonds between the bases and causes the two strands to denature
what is the second step in PCR?
Annealing: the temperature is reduced to 55’c, allowing the primers to join complementary sequences on opposite ends of each strand. The reduced temperature is necessary to allow base pairing and formation of hydrogen bonds
what is the third step in PCR?
Extension: the temperature is raised to 72’c, this is the optimum temperature for the particular DNA polymerase used in PCR. Starting from the primers, new DNA strands are synthesised in the 5’ to 3’ direction with the use of DNA polymerase and the available nucleotides
What are the results of PCR?
At the end of the first cycle, there are two copies of DNA, each copy consists of one parent strand and one new strand. Each cycle doubles the number of DNA strands.
