Set the volume the micropipettor will extract to 50 μL
Press the discharge end of the micropipettor onto an unused tip and lift
Press down plunger to the first position and insert the tip into the PCR reaction mix, just below the surface of the liquid
Gradually release the plunger and extract 50 μL of the PCR reaction mix from the tube
Remove tip from solution, wait two seconds, and then discharge all 50 μL of the PCR reaction mix into the tube (gradually push plunger down to second position) in the rack that corresponds with the patient and sample number that is being prepared for a Polymerase Chain Reaction (i.e. discharge into tube G5 1-2 for patient 1 sample 2)
Remove tip from tube, wait two seconds, and then discard the used micropipettor tip into a biological waste container (cup)
Press the discharge end of the micropipettor onto an unused tip and lift
Press down the plunger to the first position and insert the tip into the DNA primer mix, just below the surface of the liquid
Gradually release the plunger and extract 50 μL of the DNA primer mix from the tube
Remove tip from solution, wait two seconds, and then discharge all 50 μL of the DNA primer mix into the tube that is currently being prepared
Remove tip from tube, wait two seconds, then discard the used micropipettor tip into a biological waste container (cup)
Set aside the micropipettor and close the lid of the tube containing the prepared sample tightly. It should click audibly when sealed completely
Repeat Steps 5-16 for each of the remaining tubes
Once all of the tubes have all been prepared, insert the two strips of four linked tubes into the PCR machine
Allow the TA to operate the PCR machine
OpenPCR program
HEATED LID: 100°C
INITIAL STEP: 95°C for 2 minutes
NUMBER OF CYCLES: 35
Denature at 95°C for 30 seconds
Anneal at 57°C for 30 seconds
Extend at 72°C for 30 seconds
FINAL STEP: 72°C for 2 minutes
FINAL HOLD: 4°C
Research and Development
PCR - The Underlying Technology
Q1: What is the function of each component of a PCR reaction
Template DNA: This is the sequence of DNA that is intended for amplification. It will undergo extreme heat in order for it to denature.
Primers: A primer is a single strand of DNA that serves as the starting point for DNA synthesis that binds to specific DNA sequences.
Taq Polymerase: This is a thermostable enzyme that recombines nucleotides following separation by heat. It creates a new, complimentary strand of DNA through adding new nucleotides to the old ones.
Deoxyribonucleotides (dNTP's): There are the building blocks of DNA: adenine (A), thymine (T), cytosine (C) and guanine (G). These are used by the Taq Polymerase to synthesize the complementary strand of DNA.
Q2: What happens to the components (listed above) during each step of thermal cycling?
Initial step (95°C for 2 minutes): The temperature of the reaction is increased to 95°C and held for two minutes in preparation for separation.
Denature at 95°C for 30 seconds: The double stranded DNA in the reaction is broken down into single strands of DNA for amplification.
Anneal at 57°C for 30 seconds: The temperature of the reaction is lowered to around 5°C below the melting point of the primer (57°C) so that the primers will bind to specific points on the template DNA that indicate areas that will be amplified.
Extend at 72°C for 30 seconds: The temperature of the reaction is increased to the ideal temperature for polymerase activity (72°C) so that the Taq polymerase will bind to the primers that are already on the template DNA and will begin to synthesize the complimentary strand.
Final step (72°C for 3 minutes): These three minutes are used to make sure that each strand has been fully extended.
Final hold (4°C): This is the temperature to deactivate the Taq polymerase and end the process.
Q3: DNA is made up of four types of molecules called nucleotides, designated as A, T, C and G. Base-pairing, driven by hydrogen bonding, allows base pairs to stick together. Which base anneals to each base listed below?;;;
Adenine (A): pairs with Thymine (T)
Thymine (T): pairs with Adenine (A)
Cytosine (C): pairs with Guanine (G)
Guanine (G): pairs with Cytosine (C)
Q4: During which two steps of thermal cycling does base-pairing occur? Explain your answers.
Base-pairing occurs during the extended and "final step" parts of PCR. Taq polymerase is optimized during the extended phase and can attach to the primers of the template DNA strands, and during the final step the proper base pairs are gathered and attached to their correct partners.
BME 100 Spring 2015
