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)