This document discusses DNA sequencing and different methods used for DNA sequencing. It describes Sanger's dideoxy sequencing method which uses chain terminating dideoxynucleotides. The method attaches fluorescent labels to dideoxynucleotides so terminated DNA strands can be identified by their distinctive fluorescent signals. Applications of DNA sequencing include medicine, forensics, and molecular biology.

1. DNA SEQUENCING
SUBMITTED TO- SUBMITTED BY-
School of Studies ArjitaShrivastava
in Biochemistry M.Sc 3rd Sem.
Under the guidance of
Prof. Y.K. Jaiswal

2. CONTENTS :
 About DNA Sequencing.
 Methods of DNA Sequencing.
 Sanger’s dideoxy Sequencing.
 Maxam-Gilbert Sequencing.
 Automated DNA Sequencing.
 Applications.

3. DNA SEQUENCING ????
“DNA Sequencing is the process of working out
the order of the building blocks or base in a
strand of DNA.’’

5. This method uses dideoxynucleotide triphosphate
(ddNTPs) as chain terminator which have an H
on the 3’ carbon of the ribose sugar instead of
normal OH found in deoxyribonucleotide
triphosphates (dNTPs).

6. Deoxynucleotide Dideoxynucleotide
Deoxynucleotide Vs Dideoxynucleotide

8. • The seq. of ds or ssDNA molecule is determined
by treatment with chemicals that cut the
molecule at specific nucleotide positions.
PRINCIPLE: Chemical degradation
Reaction in two stages:
Chemical modification of the bases.
 Modified base is removed from sugar,
piperidine cleaves phosphodiester bond & base
is released.

10. Fluoroescent labels are attached to ddNTPs, so
each chain terminated molecule carries a single
label at its 3’end.
A different fluorochrome can be
used for each of 4 ddNTPs which has advantage
that it has no longer necessary to carry out the 4
reactions in separate tube.
So the molecules terminated
with different ddNTPs can be recognize from their
distinctive fluoroscent signals.

12. APPLICATIONS :-
MEDICINE
FORENSIC
SCIENCE
MOLECU
LAR
BIOLOGY