Biology

1. Presented By:
 Nazir Ahmed
Polymerase Chain Reaction

2. BRIEF REVIEW
 Biology; Science of life.
 Cell; Robert Hooke in1665.
 Nucleus; Robert Brown in
1831-1833.
 Nucleic Acid; Friedrick
Miescher in1869.
 DNA Model;
W.Watson&F.Crick in1953.
 Techniques to study DNA;
Kary B.Mullis in1983.

3. DISCOVERY
 Kary B.Mullis
developed this
method in 1983.
 He was awarded
nobel prize in bio-
chemistry in 1993.
Dr Kary B. Mullis, La Jolla, California, U.S.A

4. PRINCIPLE
 PCR allows rapid
production of millions
of copies of a
particular sequence
of DNA using
enzymes.
 Earlier method was
time consuming and
expensive

5. NAME
 PCR takes its name from DNA
polymerase that carries out DNA
replication in a cell.
 It is considered as chain reaction
because DNA polymerase will carry out
replication over and over again, until
there are millions of copies of the
desired DNA.

6. SPECIFICITY & SENSITIVITY
 PCR is very specific as can amplify
targeted DNA from the genomic DNA
containing thousands of genes.
 The targeted DNA sequence can be less
than one part in million of the total DNA
sample.
 Single gene or smaller piece of
DNA,among all the human
genes(<35,000) can be amplify

7. CLONING VERSES PCR
 PCR does not replace cloning.
 Cloning is still used whenever a large
quantity of gene or protein is required.

8. COMPONENTS OF PCR
 Template;
 It is targeted DNA to be
amplified.
 Primers;
 Sequence of about 20 bases
that are complementary to the
bases on either side of the
targeted DNA.
 Required for the proper
functioning of DNA polymerase
as DNA polymerase does not
start the replication process but
only continues or extend the
process.

9. Continue…
 DNA Polymerase;
 This enzyme copies the target
sequence and is
thermostabl,extracted from
the bacterium,Thermus
aquaticus which lies in hot
springs.
 It is also called Taq
Polymerase.
 Deoxyribonucleotide
triphosphate(dNTPs);
 These are substrate for the
polymerase. They are
dATP,dGTP,dCTP,dTTP.

10. HOW PCR WORKS
 Denaturation;
 The reaction is
heated to above 900c
to separate the
strands of double
helix.

11.  Annealing;
 The reaction is
cooled to 40-600c to
allow the primers to
bind to the single
stranded template
DNA.

12.  Extension;
 The reaction is
heated to720c as
polymerase is more
active at this temp.
and the targeted
sequence is copied.

13. THERMOCYCLER (PCR MACHINE)

14. APPLICATIONS OF PCR
 Inherited diseases;
 Using PCR we can identify specific portion of
DNA causing disease like sickle cell anemia.
 Cancer research;To identify oncogene and
tumor suppressor genes.
 Forensic Science ;To detect the criminal.
 Evolutionary history; To study the origin of
races of people.

15. APPLICATION CONTINUE……
 Biotechnology; To produce recombinant
products.
 paleontology; It has been possible to sequence
the DNA taken from a76,000 years old
mummified human brain and from a 17 to 20
million years old plant fossil.
 Diagnosis of Infectious diseases; like hepatitis .

16. THANK YOU