DNA has a double helix structure with two anti-parallel strands that wrap around a common axis. Each strand consists of a sequence of nucleotides containing a nitrogenous base, sugar, and phosphate. The bases on each strand form complementary base pairs with the other strand through hydrogen bonds between adenine and thymine and guanine and cytosine. This double helix structure allows DNA to carry genetic information that is used for growth, development, functioning and reproduction of organisms.

1. DOUBLE HELIX STRUCTURE OF DNA
Presented By : Prashi Jain
Roll No. : MCA/25022/18

2. DNA
 DNA – A polymer of deoxyribonucleotides.
 Found in chromosomes, mitochondria and chloroplasts.
 It carries the genetic information used in the growth ,
development , functioning, and reproduction of all known
organisms and many viruses.

3. DNA (DEOXYRIBOSE NUCLEIC ACID):
STRUCTURE
• DNA IS DOUBLE STRANDED MOLECULE THAT IS TWISTED INTO A HELIX
(SPIRALLING STAIRCASE).
DNA Double helix

4. DNA STRUCTURE
• PRIMARY STRUCTURE
• SECONDARY STRUCTURE
• TERTIARY STRUCTURE

5. DNA STRUCTURE: PRIMARY STRUCTURE
CONSISTS OF A LINEAR SEQUENCES OF NUCLEOTIDES. LINKED TOGETHER BY PHOSPHODIESTER BONDS.
• NUCLEOTIDES CONSISTS OF THREE COMPONENTS:
1. NITROGENOUS BASE
 ADENINE
 GUANINE
 CYTOSINE
 THYMINE (PRESENT IN DNA ONLY)
2. 5-CARBON SUGAR WHICH IS CALLED DEOXYRIBOSE (FOUND IN DNA) AND RIBOSE (FOUND IN RNA).
3. ONE OR MORE PHOSPHATE GROUPS.

6. Each strand consists of :-
1-nitrogeneous base
-Adenine
-Guanine
- Cytosine
- Thymine
2- A Sugar phosphate backbone

7. DNA STRUCTURE
MADE UP OF MOLECULES CALLED NUCLEOTIDES
COMPONENTS OF A NUCLEOTIDE
BASE
 SUGAR
 PHOSPHATE

8. THE SECONDARY STRUCTURE OF DNA
• TWO ANTI-PARALLEL
POLYNUCLEOTIDE CHAINS WOUND
AROUND THE SAME AXIS.
• SUGAR-PHOSPHATE CHAINS WRAP
AROUND THE PERIPHERY.
• BASES (A, T, C AND G) OCCUPY THE
CORE, FORMING COMPLEMENTARY
A · T AND G · C WATSON-CRICK
BASE PAIRS.

9. THE DNA DOUBLE HELIX IS HELD TOGETHER MAINLY BY-
HYDROGEN BONDS
HYDROGEN BOND
A CHEMICAL BOND IN WHICH A HYDROGEN ATOM OF ONE
MOLECULE IS ATTRACTED TO AN ELECTRONEGATIVE ATOM,
ESPECIALLY A NITROGEN, OXYGEN, OR FLUORINE ATOM, USUALLY
OF ANOTHER MOLECULE.

10. DNA TERTIARY
STRUCTURE
 DNA DOUBLE HELICAL
STRUCTURE COILS ROUND
HISTONES.
 NUCLEOSOMES (10NM FIBRES)
 •NUCLEOSOMES CONTAIN 146
NUCLEOTIDES

11. FUNCTIONS OF DNA
1- GENETIC INFORMATION: DNA IS THE GENETIC MATERIAL WHICH CARRIES ALL THE HEREDITY
INFORMATION.
2- REPLICATION: DNA HAS UNIQUE PROPERTY OF REPLICATION OR PRODUCTION OF CARBON COPIES.
3- MUTATIONS: CHANGES IN SEQUENCE OF NITROGEN BASES DUE TO ADDITION, DELETION OR WRONG
REPLICATION GIVE RISE TO MUTATIONS.
4- DIFFERENTIATION: DUE TO DIFFERENTIAL FUNCTIONING OF SOME SPECIFIC REGIONS OF DNA OR GENES,
DIFFERENT PARTS OOF THE ORGANISMS GET DIFFERENTIATED IN SHAPE, SIZE AND FUNCTIONS.

12. APPLICATIONS OF DNA
SCIENCE AND TECHNOLOGY HAVE ADVANCED SINCE THE DISCOVERY IN YEAR 1953.
SOME ACHIEVEMENTS THAT POTENTIALLY BECAME SUCCESSFUL DUE TO ITS INVENTION.
• CLONING
• GENETICALLY MODIFIED FOODS (GMFS)
• GENETIC ENGINEERING
• DNA FINGERPRINTING ANALYSIS

13. THANK YOU