1. Polymerase Chain Reaction
a.k.a. “How’d they get all that DNA from just a little blood?”

2. What does PCR stand for? Polymerase Chain Reaction
Developed by Kary Mullis – Nobel Prize

3. What is the goal of PCR?
To make many copies of a small section of DNA.
DNA Synthesis in vitro (in a test tube).

4. How does PCR work?
Very Similar to DNA Synthesis

5. How does PCR work? How does PCR work? (mini pcr) PCR (Kahn Academy)
National Human Genome Fact Sheet—PCR
Scientists Can Make Copies of a Gene through PCR—Nature

6. How does PCR work?
Put together DNA with oligonucleotides, primers, and polymerase
Split DNA by heating it up to 96°C
Cool mixture down for primers to bond
Heat it back up so polymerase can do its job

7. What is needed for a PCR reaction?
DNA template – DNA to be copied; “target sequence”

8. What is needed for a PCR reaction?
PCR primers – short DNA sequences; complimentary to beginning and end of target sequence

9. BUT WAIT!!!!!!!
There’s a problem here that you’ve probably already anticipated…

10. EXACTLY!!!!
If we heat up the mixture to such high temperatures, the enzymes that we rely on to run the reaction will !
denature
In the beginning, this was a problem that we solved by
adding new polymerase at the beginning of each cycle

11. HOWEVER…
We don’t have to do that anymore. How did we get around that problem???
It’s the AWESOME power of biology and the amazing critters that share the planet with us…

12. What is needed for a PCR reaction?
Taq DNA Polymerase
- copies DNA
- From heat loving bacteria Thermus aquaticus.
- Can survive hot temperatures needed in PCR reaction

13. What is needed for a PCR reaction?
Nucleotides – building blocks of DNA
Thermalcycler – computerized to change temperatures

14. What is needed for a PCR reaction?
MgCl2 – part of buffer, all enzymes need the correct buffer (acid + salts) to work
MgCl2

15. What are the 3 main steps of PCR?
Denaturing – DNA strands separate at hydrogen bonds
Temperature = 950C

16. What are the 3 main steps of PCR?
Annealing – Primers bind
Temperature is dependent on primer sequence
Annealing temperature = 3(G+C) + 2(A+T)
# of H-bonds between nucleotides

17. What are the 3 main steps of PCR?
Extension – DNA is copied
Temperature = 720C

18. PCR Reaction Summary
1. Denaturing
2. Annealing
3. Extension
30 cycles

19. How many times can target DNA be copied?

20. What would someone do with PCR?
Forensics
Identification of corpses or body parts.
Analysis of pathogens.
Eliminate or link suspects to scene of crime through a sample (blood, human hair, skin, semen) left at scene or circumstantial links (pet hair, plant parts).

21. What would someone do with PCR?
Medical (genotyping)
Genetic diseases identified pre- or post-natally.
Cancers identified and classified.
Identifying bacterial or viral strains for proper treatment.

22. What would someone do with PCR?
Food Science
Samples can be tested for genetic engineering traits.
Bacterial contaminants and source of contamination can be quickly identified.
Pedigrees and traits of valuable animal food stocks can be verified.

23. What would someone do with PCR?
Relationships
Paternity.
Evolution – developing relationships between organisms or studying extinct species from museum specimens.
Ecology – tracking organisms or defining biodiversity by identifying unique species.

24. PCR Review Music Video
BioRad “When You Need to Find Out Who The Daddy Is”
BioRad “GTCA”