polymerase chain reaction Flashcards
1
Q
describe the first stage of PCR (mixing)
A
DNA to be amplified placed in thermocycler with:
- excess nucleotide bases
- DNA primer
- DNA polymerase
2
Q
describe the second stage of PCR (denature)
A
temperature is increased to 95ºC which denatures DNA sequence
- H bonds break, separating the strand into 2
3
Q
describe the third stage of PCR (priming)
A
temp is reduced to 55ºC
- primers anneal to DNA
4
Q
describe the fourth stage of PCR
A
temp increases to 72ºC
- Taq polymerase adds bases to primer
- build complimentary DNA strands identical to original DNA sequence
5
Q
how many times does the PCR cycle repeat?
A
40 times
6
Q
why is Taq polymerase used instead of DNA polymerase?
A
- Taq polymerase is harvested from bacteria that live in hot springs - able to withstand higher temperatures
- DNA polymerase would not be able to withstand 95ºC
