The PCR Dash
SWBIC Educational Resources
The Polymerase Chain Reaction is a technique used very extensively in molecular
genetics, forensics and other fields to greatly amplify a specific DNA
sequence. Kary Mullis who received the 1993 Nobel Prize in Physiology and
Medicine for the discovery invented it in 1983.
A PCR amplification reaction includes: the source DNA containing the sequence
of interest (as few as 1 copy), two unique single-stranded DNA primers that
bracket the desired sequence, deoxyribonucleotides (the building blocks of
DNA), and Taq DNA polymerase (from the thermophilic organism
Thermus aquaticus). The reaction is cycled between three temperatures that
facilitate the construction of new copies of the desired DNA sequence.
At 95°C, the double stranded source (or template) DNA is denatured
into single strands. Then, at 55°C, the primers bind (anneal) to
complimentary sequences on the template DNA that bracket the sequence to
be amplified. Last, at 72°C, the Taq DNA polymerase adds
deoxyribonucleotides in sequence to the primer as it builds a complementary
strand to the template DNA. This cycle is repeated until a very large number
of copies are obtained. The reaction is usually carried out in a machine
called a thermal cycler that quickly changes the temperature of the reaction
mixture between the three necessary temperatures. A good graphic illustration
of the process can be found at
The PCR Dash is a game that will help illustrate the PCR process for students.
The game is best played by several teams in a fun competition. Each team
should have 4 people.
Due to the nature of the exercises, the file should be downloaded and opened
with Microsoft Word.
- The PCR Dash (Microsoft Word)
- The PCR Dash (Web Format)
Microsoft Word Viewer (size: 3952016 bytes) is a free utility available
for download from the Microsoft WWW site.