Polymerase chain reaction (PCR) is a process used to amplify a specific DNA sequence. It involves 3 main steps - denaturation, annealing, and extension - that are repeated in cycles to exponentially increase the number of copies of the DNA target. During denaturation, the DNA is heated to separate the double strands. Annealing allows primers to bind to the single strands. Then during extension, an enzyme synthesizes new strands complementary to the templates, doubling the number of DNA molecules with each cycle. Repeating this process many times can generate billions of copies of the target sequence from very small initial samples.

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It’s a process to get billion copies of a
specific DNA fragment.
The need for this when the genetic sample is
very few to process for a specific
examination.
example-DNA FINGER PRINTING,DNA
CLONNNG ,

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PCR involved in 3 main step.
THESE 3 STEPS COLLECTIVLY CALLED AS “ONE
PCR CYCLE.
THE STEPS ARE 1. Denaturation
2. Annealing
3.extension

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THIS STEP INVOLEED IN CHANGING THE
DOUBLE strand DNA into single strand DNA.
FOR THIS WE MUST INCREASE TEMPERATURE
TO 94°C.

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DENATURED DNA strand are then exposed
into DNA PRIMERS
THERE ARE THREE DNA PRIMERS FOR
IDENTIFY SEQUENCE ,anti-sequence of a DNA
strand
Then a enzyme call “taq-polymerase” that a
new DNA strand from DNA building-blocks.
The best temperature for this step is 50–
65 °C

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This step temperature increasd to 75–80 °C.
At this step the DNA polymerase synthesizes
a new DNA strand complementary to the DNA
template strand .
Now the DNA is became double stranded
again.
After 1st cycle now we have 4 samples.
If we repeat again after 2nd step 8 sample will
be resulted.

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After 3 rd cycle we will get 16 samples
After 30 cycles we will get 230 =
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