DNA is the genetic material found in chromosomes, mitochondria, and chloroplasts of most organisms. It has a double-helix structure and is usually double-stranded. DNA is composed of deoxyribonucleotides, which each contain a deoxyribose sugar, a phosphate group, and one of four nitrogenous bases. Similarly, RNA is composed of ribonucleotides and usually single-stranded. It contains a ribose sugar rather than deoxyribose and usually contains the base uracil instead of thymine. Both DNA and RNA have a nucleotide structure that forms the backbone of their polymer chains.

2. DNA
 Deoxyribonucleic acid
 DNA - a polymer of deoxyribo-
nucleotides.
 Usually double stranded.
 And have double-helix structure.
 found in chromosomes,
mitochondria and chloroplasts.
 It acts as the genetic material in
most of the organisms.
 Carries the genetic information

3.  DNA Structure
DNA has three main components
1. Deoxyribose (a pentose sugar)
2. Base (there are four different ones)
3. Phosphate
 DNA structure is often divided into four
different levels primary, secondary,
tertiary and quaternary.

4.  Nucleotide Structure
 Nucleotides are formed by the condensation of a sugar,
phosphate and one of the 4 bases
 The following illustration represents one nucleotide
HH
H
O
CH2
Base
Phosphate
Deoxyribose
5′
OH
4′ 1′
3′ 2′
O
O OP
O–
HH
Nucleotide

5. RNA
 Ribonucleic Acid
 RNA is a polymer of
ribonucleotides linked together by
phosphodiester linkage.
 RNA was first genetic material.
 Usually single stranded and helical
in structure.
 But double stranded also present
in some viruses

6. RNA structure
 There are also three main component
a) Phosphate Group
b) Sugar(Ribose)
c) And Nitrogenous base
 Nucleotide
HH
OH
O
CH2
Base
Phosphate
Ribose
OH
5′
4′ 1′
3′ 2′
O
O
P
O–
O
HH
A, G, C or U
RNA Nucleotide