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Polymerase Chain Reaction (PCR). U.S. Department of Energy Genomics:GTL Program http://www.ornl.gov/hgmis. Introduction to PCR. Genome : composed of DNA, is our hereditary code (the “blueprint”)
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U.S. Department of Energy Genomics:GTL Program http://www.ornl.gov/hgmis
Introduction to PCR • Genome: composed of DNA, is our hereditary code (the “blueprint”) • Molecular biology: the study of genes and the molecular details that regulate the flow of genetic information from DNA to RNA to proteins, from generation to generation. Biotechnology uses this knowledge to manipulate organisms’ DNA to help solve human problems.
History of PCR • 1983 Kary Mullis (Cetus Corp) developed the molecular biology technique that has revolutionized genetic research: Polymerase Chain Reaction • PCR quickly transformed molecular biology into a multidisciplinary research field.
Why PCR? • With PCR, you can target and make millions of copies (amplify) a specific piece of DNA (or gene) out of a complete genome.
How PCR is used • PCR impacted several areas of genetic research: • PCR used as a medical diagnostic tool to detect specific mutations that may cause genetic disease • PCR used in criminal investigations and courts of law to identify suspects • PCR used in the sequencing of the human genome
DNA Basics • Double Helix • Ladder • Sides = Phosphate/ Sugar backbone • Rungs (steps) = Nucleotides • A, T, C, G • Also called bases http://www.pbs.org/wgbh/nova/genome/dna.html
PCR Amplification • PCR makes use of the same basic processes that cells use to duplicate their DNA (replication) • Complementary DNA strand hybridization • DNA strand synthesis via DNA polymerase
Recipe for PCR Amplification • DNAsample: containing the intact sequence of DNA to be amplified • MASTER MIX: • Free nucleotides (dNTPs): raw material of DNA (A,T,C,G) • DNApolymerase (Taq polymerase): enzyme that assembles the nucleotides into a new DNA chain • Primers: pieces of DNA complementary to the template that tell DNA polymerase exactly where to start • Flourescent dye: “lights up” when it binds to complete DNA strands
PCR Equipment • Thermocycler: • A thermocycler is used to rapidly heat and cool DNA samples to facilitate DNA amplification.
Steps of PCR • Denaturation (94 degrees, 1min) • Annealing (60 degrees, 1min) • Elongation (72 degrees, 2min)
Denaturation • Heating phase (94°C) • Causes the two strands that make up a piece of DNA to separate.
Annealing • The temperature is dropped (52°C). • Primers attach (i.e., anneal) to the single-stranded • DNA.
Elongation • Temperature is raised (72°C). • DNA polymerase (Taq polymerase) takes free nucleotides and adds them to the end of the primer. • A new double stranded piece of DNA is created that is identical to the original piece of DNA that you are trying to replicate.
Result of PCR • ~30 cycles • Amplified exponentially • Results in 1.1x1012 sets of precise-length DNA
Information Resources • http://www.dnai.org/d/index.html • http://gslc.genetics.utah.edu/teachers/tindex/index.cfm?switch=single&unitid=basics • http://www.bioteach.ubc.ca/TeachingResources/ • http://genetics-education-partnership.mbt.washington.edu/ • http://genome.pfizer.com/index.cfm • http://www.bioteach.ubc.ca/MolecularBiology/DNAfingerprint/index.htm • http://www.genome.gov/Pages/EducationKit/online.htm • http://www.pbs.org/wgbh/harvest/engineer/ • http://www.pbs.org/wnet/secrets/lessons/lp_virus.html • http://www.ornl.gov/sci/techresources/Human_Genome/education/education.shtml • http://www.forensic.gov.uk/forensic_t/index.htm • http://gslc.genetics.utah.edu/features/forensics/ • http://health.discovery.com/minisites/dna/zs_forensics.html • http://www.denverda.org/legalResource/Overview.pdf