Function and design
Biometra TOne
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3
Function and design
3.1
Principle of operation
Developed in 1983 by Kary Mullis, PCR (polymerase chain reaction) now is a common
and indispensable technique used in medical and biological research laboratories.
The end-point thermal cycler amplifies nucleic acids by repeated cycles of heating and
cooling using DNA polymerases reaction.
A typical PCR program comprises the following steps:
Step no.
Step
Temperature
(example)
Explanation
1
Initial denaturation
95 °C
¡
Initial denaturation of the DNA
strand: Division into two single
strands
¡
Activation of the enzyme poly-
merase
2
Denaturation
95 °C
Denaturation: Division of the prod-
ucts of the PCR reaction into two sin-
gle strands
3
Annealing
55 °C
Annealing of the primer pair consist-
ing of forward and reverse primers
which define the beginning and the
end of the characteristic DNA section
4
Elongation
(or extension)
70 °C
Strand extension: Construction of the
complementary DNA strand by the
enzyme polymerase and with the aid
of free nucleotides starting at the
primer
5
Final elongation
70 °C
Final strand extension
6
Final retention
10 °C
Retention of the amplified samples
until execution of the measurement
or further processing
The PCR program shown by way of example reiterates steps 2 to 4 cyclically in order to
double a characteristic DNA section with each cycle. The number of products increases
exponentially.
The device combines latest technology with ergonomic design and user-friendly soft-
ware. The user interface consists of a touch screen. The screen displays the time, status
and the temperature program for each cycle in form of a diagram or a table. You can use
the touch screen keyboard to enter information and program parameters directly on the
screen.
