PCR Flashcards
What does PCR do?
Amplifies amount of DNA present. Doesn’t identify DNA.
Four steps:
Denaturing / melting.
Annealing.
Elongation.
Repeat process.
Three uses of PCR:
Crime scene DNA.
Paternity testing: NAATs.
Chlamydia testing.
Cannot be used for extraterrestrial life because…..
There won’t be primers available to use if the organism is unknown.
Enzyme used is:
Taq polymerse.
RNA has only one strand, T is replaced with…
U.
Each strand con only be copied from the
3’ end to the 5’ end.
Step one: denaturing / melting ….
Temp is at 94 degrees to break H bonds between DNA strands.
The primer tells the enzyme which section of DNA is to be amplified.
This step isn’t needed for RNA as it’s already a single strand.
Steps two: annealing….
The primers are bonding. Temp is dropped to 54 degrees as we want primers to anneal to stands and new H bonds to form.
Wh is excess primer used?
To optimise number of copies.
STR - Short tandem repeats are….
The region of interest which is to be amplified.
Each cycle doubles the amount of DNA in section of interest and takes approx….
Five minutes per cycle.
Steps three: Elongation.
Temp is at 72 degrees, optimum for TQ enzyme. The enzyme can bind without primers.
Step four: Repeat process…
Strands are shorter. Just three sections, primer-STR-primer.
Two chromosomes may have diff number of….
Repeats in the STR section.
