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Background Session #5 Polymerase Chain Reaction and Primer Choice May 31, 2008. Dr. Simona Bartl Adjunct Professor Moss Landing Marine Labs. Intro to the Polymerase Chain Reaction (PCR). Definition. A procedure to amplify a specific DNA region Using DNA synthesis (DNA replication)
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Background Session #5Polymerase Chain Reaction and Primer Choice May 31, 2008 Dr. Simona Bartl Adjunct Professor Moss Landing Marine Labs
Intro to the Polymerase Chain Reaction (PCR) May 31st Workshop
Definition • A procedure to amplify a specific DNA region • Using DNA synthesis (DNA replication) • Yields millions of copies of the target region • Makes enough DNA for further work • Is the first step in preparing DNA for: • DNA Sequencing • Restriction Digestion • Cloning and Bacterial Transformation Diagram by Andy Vierstraete 1999 May 31st Workshop
Amplification steps May 31st Workshop
Application Examples • PCR is commonly used to… • Identify species • Identify alleles/genotypes to assess variability in a population • Conduct forensic investigations • Create sequences for phylogenies1 to determine taxonomic relationships2 1 evolutionary history 2 according to scientific classifications May 31st Workshop
Non-examples • PCR is NOT used to: • Amplify RNA or proteins • Construct traditional genomic or cDNA libraries • Make monoclonal antibodies • Conduct stem cell research May 31st Workshop
Materials • PCR is DNA Synthesis • DNA template • Can be DNA extracted or purified from an organism • Primers • Anneal to single-stranded DNA template • Provide initiation site for extension of new DNA • Forward primer - Anneals to DNA anti-sense strand1 • Reverse primer - Anneals to DNA sense strand2 1 template strand for transcription 2 identical to mRNA sequence May 31st Workshop
Primers http://www.flmnh.ufl.edu/cowries/PCR.gif May 31st Workshop
Materials • DNA polymerase • Enzyme that extends growing DNA strand complementary to DNA template • Taq polymerase - thermostable enzyme from Thermophilus aquaticus1 • dNTP’s • Nucleotides (Adenine, Cytosine, Guanine, Thymine) building blocks for new DNA strands • Buffer and Ions • Provides optimal conditions for enzyme 1 Bacteria isolated from hot springs May 31st Workshop
Amplification Steps 1. Denature double-stranded DNA 2. Anneal primers to single-stranded DNA 3. Extend primers, yielding new double-stranded DNA Cycling:Repeat steps 1 through 3 (20 - 40 times) May 31st Workshop
Equipment Wikimedia Commons May 31st Workshop
PCR Animation - 3D PCR Animation - 2D May 31st Workshop
Primer choice • Conserved DNA regions that flank a more variable region • Conserved so primers will anneal (stick) and therefore allow DNA synthesis • Variable so DNA data will be informative May 31st Workshop
www-personal.umich.edu May 31st Workshop