Spectrum Biology - September 2016

NUCLEIC

ACIDS

OUR HEREDITARY

COMMANDERS

Nucleic acids are the informational molecules of the cell. They constitute the genetic material of all living things as well as

of viruses. Within the structure of nucleic acids are coded the ‘instructions’ that govern all cellular activities. Almost every

cell of a multicellular organism contains the same complement of genetic material–its genome. Chromosomes, the nucleic

acid molecules that are the repository of an organism’s genetic information are the largest molecules in a cell. In this article

we will discuss about role of nucleic acids in transferring genetic information from one generation to the next generation

as well as in the formation of new species.

Composition of Nucleic Acid

Nucleic acids are long, thread-like macromolecules built up

of nucleotides. Hydrolysis of a nucleotide yields three

component substances, a pentose sugar, nitrogenous base

and phosphoric acid. The structure of nucleic acid is as

follows:

Some Common Nucleosides and Nucleotides

Base + Sugar → Nucleoside + H PO 34 → Nucleotide

Adenine Adenosine Adenylic acid

Thymine Thymidine Thymidylic acid

Uracil Uridine Uridylic acid

Cytosine Cytidine Cytidylic acid

Guanine Guanosine Guanylic acid

Nucleic Acid Types

Two types of nucleic acids are found in living cells.

 Deoxyribonucleic Acid (DNA)

 Ribonucleic Acid (RNA)

Most of the DNA is found in the nucleus, while there is

some RNA in the nucleus and most is in the cytoplasm,

particularly in the ribosomes.

Nucleic acid

Nucleotides

(Nucleoside)

Nitrogenous

base

(Purine or

pyrimidine)

Pentose

sugar

(Deoxyribose

or ribose)

Phosphoric acid

P OH

OH

OH

NH 2

N

N

N N

HOH C 2 O

OH

Base

Pentose

sugar

Nitrogenous
base + sugar

NH 2

N

N

N N

O

OH

P O

O

H

O

HO CH 2

+ Phosphoric

acid

(Nucleoside) Adenylic acid (Nucleotide)