This document provides information on nucleic acids and their components. It discusses that nucleic acids are macromolecules composed of nucleotides that are polymers of either RNA or DNA. The key components of nucleotides are nitrogenous bases, the pentose sugar ribose or deoxyribose, and a phosphate group. Nucleotides serve as monomers that bond together to form nucleic acid polymers through phosphodiester linkages between the 3' carbon of one sugar and the 5' carbon of the next. The document compares the key differences between DNA and RNA such as their bases, sugars, and functions.

2. Nucleic Acids
Macromolecules/ Biopolymers
 Polymers of Nucleotides
RNADNA

3. History
Freidrich Miescher isolated from the nuclei of
pus cells.
 Named as nuclein.
 Nuclein posses acidic properties.

4. Role of Nucleotides
Building blocks of nucleic acids (DNA, RNA).
 Energy currency in cellular metabolism (ATP).
Structural components of many enzymes
cofactor. (NAD, FMN, FAD)

5. Component of Nucleotides
Base
Sugar
Phosphate Group
Nucleotides = Base + Sugar + Phosphate
Nucleoside= Base + Sugar
Nucleotides = Nucleoside + Phosphate
Nucleotides : Monomers of Nucleic Acid

6. Base
Nitrogenous Bases
Aromatic
Heterocyclic
Pyrimidines Purines

7. Sugar
Monosaccharide
Five-Member Closed Ring
Pentose
β-furanose form

8. Phosphate
Monophosphate/ Diphosphate/ Triphosphate
The Phosphorous atom is pentavalent.

9. Structure of Nucleotides
Base: Adenine Base: Thymine
Sugar: D- Ribose
Sugar: D-2-Deoxyribose
Phosphate:
Monophosphate
Phosphate: Diphosphate

10. Binding in Nucleotides
 N-1 of Pyrimidines and N-9 of Purines are bound to the C-1’
of the pentose.
 The covalent bond linking the base and sugar is called N-β-
glycosidic bond.
Phosphate group is esterified at the 5' carbon of pentose.
Nucleotides are covalently linked to another through
phosphate-group bridges / phospho diester linkage, formed
between the 3'- OH of a pentose and the 5'- OH of the next
pentose.
The sequence of a single strand of is always written as 5’ →3’
direction.
The backbone of consists of Sugar Phophate covalent
linkage.
5’
3’

11. Components of DNA and RNA
RNA
DNA
Bases : Adenine, Guanine, Cytosine, Thymine
Sugar : D-2-Deoxyribose
Phosphate
Bases : Adenine , Guanine, Cytosine, Uracil
Sugar : D-Ribose
Phosphate

12. Nomenclature of
Nucleosides and Nucleotides
Bases Nucleoside Nucleotide
Adenine (A) Adenosine Adenylate (AMP)
Guanine (G) Guanosine Guanylate (GMP)
Cytosine (C) Cytidine Cytidylate (CMP)
Uracil (U) Uridine Uridylate (UMP)
Bases Nucleoside Nucleotide
Adenine (A) Deoxyadenosine Deoxyadenylate (dAMP)
Guanine (G) Deoxyguanosine Deoxyguanylate (dGMP)
Cytosine (C) Deoxycytidine Deoxycytidylate (dCMP)
Thymine (T) Deoxythymidine Deoxythymidylate (dTMP)
RNA
DNA

13. Comparison of DNA & RNA
Feature DNA
(Deoxyribose Nucleic Acid)
RNA
(Ribose Nucleic Acid)
Location Nucleus Cytoplasm
Bases Purine: Adenine, Guanine
Pyrimidine : Cytosine, Thymine
Purine : Adenine, Guanine
Pyrimidine : Cytosine ,Uracil
Sugar D-2-Deoxyribose D-Ribose
Strand Nature Double Stranded Single Stranded
Function Carries Genetic Information Synthesis of Proteins
Susceptibility to
Alkali Hydrolysis
Easily hydrolyzed due to the presence of
OH group at C-2’ position of sugar, forms
2',3'-cyclicdiester of mononucleotides.
Resists alkalis due to the absence of OH
group at C-2’ position of sugar.

14. Stabilising Forces
Base Pairing : Hydrogen bonding between
complementary base pairs.
Base-Stacking : Van der Waals interactions and π-π
interactions among planar bases.
Hydrophobic interactions : Nonpolar bases bury them away
from water.
Hydrophilic interactions : Polar Sugar phosphate backbone
interact with H2O and cations .

15. Base Pairing
Horizontal Interaction.
Non covalent interactions in which H atom forms
bond with an electronegative atom.
Among Purines and Pyrimidines
(Complementary Base Pairs)
A=T /U 2 hydrogen bonds
 G≡C 3 hydrogen bonds

16. H-Bonding
H bonding among
Complementary
Base Pairs

17. Base Stacking
Vertical Interaction.
Non-Covalent interaction among the planar bases
parallel to another separated by vander wall radii
(3. 14 A o).
π-π interactions among aromatic rings.
Strongest Force of Interaction.

18. Vander Wall & π-π interactions
A
A
G
T
T
C
C G
π-π interactions among
Aromatic BasesVander wall Interactions
among Non Polar Bases

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