2. 

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 ,

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

4. 

THIS STEP INVOLEED IN CHANGING THE
DOUBLE strand DNA into single strand DNA.
FOR THIS WE MUST INCREASE TEMPERATURE
TO 94°C.

5. 




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

6. 




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.

7. 

After 3 rd cycle we will get 16 samples
After 30 cycles we will get 230 =
1073741824