Nucleic Acid.ppt - Nucleic Acid DNA & RNA By: Sanjay...

Nucleic Acid
(DNA & RNA)
By: Sanjay Mahato
IAAS, Lamjung

Definition of Nucleic Acid:
•
Although the name nucleic acid suggests their location in the nuclei of
cells, certain of them are, however, also present in the cytoplasm.
•
The nucleic acids are the hereditary determinants of living orgainsms.
•
They are the macromolecules present in most living cells either in the free
state or bound to proteins as nucleoproteins.
•
Like the proteins, the nucleic acids are biopolymers of high molecular
weight with mononucleotide as their repeating units, just as amino acids
are the repeating units of proteins.
•
As regards their elemental composition, the nucleic acids contain carbon,
hydrogen, oxygen, nitrogen and, strangely enough, phosphorus.
•
The structure of every protein, and ultimately of every cell constituent, is a
product of information programmed into the nucleotide sequence of a
cell’s nucleic acids.

Types of Nucleic Acids:
•
There are two kinds of nucleic acids, deoxyribonucleic acid (DNA) and
ribonucleic acid (RNA).
•
Both types of nucleic acids are present in all plants and animals.
•
Viruses also contain nucleic acids; however, unlike a plant or animal, a
virus has either RNA or DNA, but not both.
•
DNA is found mainly in the chromatin of the cell nucleus whereas most of
the RNA (90%) is present in the cell cytoplasm and a little (10%) in the
nucleolus.

Structural components of RNA and DNA:

Basically, following components are found in a nucleic acids:
1. Phosphoric Acids
2. Pentose Sugar
3. Nitrogenous bases
Components Ribonucleic Acid
(RNA)
Deoxyribonucleic Acid
(DNA)
Acid Phosphoric Acid Phosphoric Acid
Pentose Sugar D-ribose D-2-deoxyribose
Nitrogenous Bases:
Purine: Adenine;
Guanine
Adenine;
Guanine
Pyramidine: Cytosine;
Uracil
Cytosine;
Thymine

1. Phosphoric Acids:
•
The molecular formula of phosphoric acid is H3PO4.
•
It contains 3 monovalent hydroxyl groups and a divalent oxygen atom, all
linked to the pentavalent phosphorus atom.

2. Pentose Sugar:
•
The two types of nucleic acids are distinguished primarily on the basis of
the 5-carbon keto sugar or pentose which they possess. One possesses D-
2-deoxyribose, hence the name deoxyribose nucleic acid or
deoxyribonucleic acid, while the other contains D-ribose, hence the name
ribose nucleic acid or ribouncleic acid.

3. Nitrogenous bases:
•
Two types of nitrogenous bases are found in all nucleic acids.
•
The base is linked to the sugar moiety by the same carbon (C1) used in
sugar-sugar bonds.
•
The nitrogenous bases are derivatives of pyrimidine and purine.
a. Purine derivatives:
•
The prevalent purine derivatives found in nucleic acids are adenine and
guanine.
b. Pyrimidine derivatives:
•
The prevalent pyrimidine derivatives found in nucleic acids are: Uracil,
Thyamine and Cytosine.

Structures of Purines & Pyramidines