The Original Design
A PCR machine, or Polymerase Chain Reaction machine, produces copies of DNA which are then used to produce thousands, even millions, of copies of strands from a certain segment of DNA using a heating cycle. It can also be used to detect and/or diagnose certain diseases based on a person's DNA. It can also be used as a DNA fingerprinting machine, which is critical to forensic scientists when solving a murder (match DNA samples from suspects), and paternity testing.
Experimenting With the Connections
When we unplugged (part 3) from (part 6), the LCD screen on the machine remained lit, but did not display any information on the screen.
When we unplugged the white wire that connects (part 6) to (part 2), the machine
Test Run
We first tested the Open PCR machine on October 23, 2013. During this test run we had unsuccessful result, as our Open PCR machine failed to operate.
Protocols
Thermal Cycler Program
1. Denature for one cycle at 95C for three minutes (Initial hold)
2. Run through 35 cycles of denaturing, annealing, and extending (the heating and cooling makes the DNA stronger)
Denature: Heat the DNA to 95C for 30 seconds
Anneal: Cool the DNA to 57C for 30 seconds
Extend: Heat the DNA back to 72C for 30 seconds
3. Extend the DNA at 72C for 3 minutes (to stabilize the DNA)
4. Finally, the DNA is cooled at 4C to slow down any reactions and prepares the DNA for storage
DNA Sample Set-up
Tube C+
Positive Control: Cancer DNA Template
Tube 1A
Patient 1
ID: 54764
Tube 1B
Patient 1
ID: 54764
Tube 1C
Patient 1
ID: 54764
Tube C-
Negative Control: Non-cancer DNA template
Tube 2A
Patient 2
ID: 51843
Tube 2B
Patient 2
ID: 51843
Tube 2C
Patient 3
ID: 51843
DNA Sample Set-up Procedure
Step 1
Step 2
Step 3...
PCR Reaction Mix
What is in the PCR reaction mix?
DNA/ primer mix
What is in the DNA/ primer mix?
Research and Development
'PCR - The Underlying Technology'
'Components of a PCR Reaction'
Polymerase Chain Reactions require several components to ensure the effective amplification of the target DNA.
For PCR to occur, template DNA is necessary. Template DNA is the sample DNA used in the PCR reaction that contains
the target region, or section of DNA that is to be amplified. When the template DNA is denatured, it is separated into two strands.
Each strand is used as a template for the construction of a complementary DNA strand. Another component of a PCR reaction is primers.
Primers are short pieces of single-stranded DNA that are complementary to a section of the template strand. In order to ensure the
amplification of the target sequence, two primers are used: a forward primer and a reverse primer. A forward primer induces the elongation of
the DNA strand from the 5' to the 3' direction, while the reverse primer initiates the elongation of the DNA strand from the 3' to the 5' direction.
In this way, the primers begin the construction of complementary DNA strands to each strand of the template DNA at the location of the target DNA.
Taq polymerase initiate the production of new strands of DNA by connecting to dNTP (deoxyribonucleotides triphosphate) to match with the target sequence
of the DNA. Magnesium Chloride (MgCl2) is the polymerase that needs a divalent cation to function correctly. This bonds assists by being a cofactor when
the polymerase and the DNA strand bind together. The polymerase with the hydroxide group is required for the bind and helps in removing the hydrogen from the
deoxyribose of the nucleotides, in order to add the next nucleotide. Deoxyribonucleotides, or dNTPs, are extra bases which are building blocks for the new DNA strand.
'Steps of Thermal Cycling'
Thermal cycling initial starts at 95°C for three minutes during this period of time the enzymes are activated due to the optimal temperature that taq
polymerase will become active. During this step the single stranded DNA template will also begin to disconnect. The next step is Denature which will be at
95°C for 30 second throughout this time period the hydrogen bonds with the complementary bases will begin to become distorted ultimately causing the DNA
melting of the DNA template producing a single-stranded DNA molecule.
Following denaturation, the DNA undergoes annealing, where primers form stable DNA-DNA hydrogen bonds with the template DNA. After the template DNA
and the primers have bound, the DNA polymerase attaches to the primer-template hybrid. Annealing occurs at 57 degrees Celsius for 30 seconds.
Then, extension occurs at 72 degrees Celsius for 30 seconds. During extension, the DNA polymerase enzyme synthesizes a new strand of DNA complementary
to the template strand by adding dNTPs complementary to the bases of the template strand in the 5' to 3' direction.
During the final step which occurs at 72 degrees Celsius for duration of three minutes any remaining single stranded DNA that is leftover will become fully extended.
Also during the final step, the final hold occurs at four degree Celsius, which is when the entire reaction becomes stored.
'Base pairing'
Base pairing is the attachment of certain nucleotide bases to others to form a double-stranded DNA molecule.
When primers attach to the template, base pairing allows for the creation of hydrogen bonds that allow them to stick together.
The four nucleotide bases that comprise DNA are: Adenine (A), Thymine (T), Guanine (G), and Cytosine (C. Adenine and Thymine bind to each other,
and Guanine and Cytosine bind to each other. This means that a "G" nucleotide base on the template strand will bind to a "C" nucleotide base on the primer.
While the "A" nucleotide base on the temple strand will bind to the "T" nucleotide base on the primer.
All of these nucleotides are take by the taq polymerase in for sequencing in the DNA template.