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Polymerase Chain Reaction (PCR) 2B - Coggle Diagram
Polymerase Chain Reaction (PCR) 2B
PCR Basics
The
polymerase chain reaction
(PCR) is a technique for the amplification of DNA in vitro (outside the body).
What’s a primer?
A primer is a
short sequence of nucleotide
formed
at the 3’ end of a parent DNA strand that is going to be replicated
.
Requirements for PCR
-
Sequence specific primers
– these are designed by the scientist and can be manufactured by a machine.
In PCR,
primers are complementary
to
specific target sequences
at the two ends of the region to be amplified
Thermal Cycling/ PCR Process
1)
DNA heated
between
92-98 degrees
C to
denature
and therefore
separate the strands
2) The separate
strands are cooled
to between
50-65
degrees C
allow primers
complementary
to specific target sequences
at the two ends of the region
to bind
3) Special
heat-tolerant DNA polymerase
is used to
replicates the DNA
by
adding free bases to the primers.
4) The
DNA strand has doubled
. Repeated cycles doubles the number of strands repeatedly.
Why do we need/use PCR?
To be able to have enough DNA from a sample so that it can be analysed,
we need to amplify and increase the number of copies, so that the results can be observed.
PCR allows for an exponential replication in an efficient time frame.
Gel Electrophoresis
Separates DNA
molecules
based on size
Relies on the
negative charge
of DNA molecules to work.
Uses of PCR
Archeological analysis
Ancient DNA, degraded over the years, can be amplified and used in archaeological, paleontological and evolutionary research.
Disease detection
DNA sequences that are known to indicate certain genetic disorders or diseases are amplified using PCR for the purposes of diagnosis.
Population Studies
-
Analysis of human or other species’ population genetics
can be rapidly performed using PCR analysis.
DNA Profiling
PCR helps to rapidly identify people. Specific areas of DNA known to vary between individuals is amplified. Giving different sized fragments in different people