Nucleic Acid: Definition Structure And Functions

definition: Nucleic acids are long-chain polymeric molecules, the monomer (the repeating unit) is known as the nucleotides and hence sometimes nucleic acids are referred to as polynucleotides.

The first isolation of nucleic acid we now refer to as DNA was accomplished by Swiss physiologist Johann Friedrich Miescher circa 1870 while studying the nuclei of white blood cells. In the 1920’s nucleic acids were found to be major components of chromosomes, small gene-carrying bodies in the nuclei of complex cells. Elemental analysis of nucleic acids showed the presence of phosphorus, in addition to the usual C, H, N & O. We now know that nucleic acids are found throughout a cell, not just in the nucleus, the name nucleic
acid is still used for such materials.
A nucleic acid is a polymer in which the monomer units are nucleotides.

Types of Nucleic Acids

There are two Types of Nucleic Acids:
DNA: Deoxyribonucleic Acid: Found within cell nucleus for storing and transfering of genetic information that are passed from one cell to other during cell division
RNA: Ribonucleic Acid: Occurs in all parts of cell serving the primary function is to synthesize the proteins needed for cell functions.
The nucleic acids are very large molecules that have two main parts. The backbone of a nucleic acid is made of alternating sugar and phosphate molecules bonded together in a long chain, Each of the sugar groups in the backbone is attached to a third type of molecule called a nucleotide base.

1. DNA

In most living organisms (except for viruses), genetic information is stored in the molecule deoxyribonucleic acid, or DNA. DNA is made and resides in the nucleus of living cells. DNA gets its name from the sugar molecule contained in its backbone(deoxyribose); however, it gets its significance from its unique structure. Four different nucleotide bases occur in DNA:

adenine (A), cytosine (C), guanine (G), and thymine (T).

What are the components of a DNA molecule? - Quora

Ribonucleic Acid (RNA)

The RNA molecule is also composed of phosphoric acid, a pentose sugar and some cyclic bases containingnitrogen. RNA has β-D-ribose in it as the sugar moiety. The heterocyclic bases present in RNA are adenine (A), guanine (G), cytosine(C) and uracil (U). In RNA the fourth base is different from that of DNA. The RNA generally consists of a single strand which sometimes folds back; that results in a double helix structure.

DNA vs. RNA | Biology Dictionary

There are three types of RNA molecules, each having a specific function:

  1. messenger RNA (m-RNA)
  2. ribosomal RNA (r-RNA)
  3. transfer RNA (t-RNA)

The Functions of Nucleic Acids

        1. Nucleic acidsare responsible for the transmission of inherent characters from parent to offspring.
        2. They are responsible for the synthesis of protein in our body
        3. DNA fingerprinting is a method used by forensic experts to determine paternity. It is also used for the identification of criminals. It has also played a major role in studies regarding biological evolution and genetics.

Also read : Lipids: Definition , structure, function and classification

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