Nucleic acids: Definition, Classification, Functions

Nucleic acids

Nucleic acids are a polynucleotides consisting of repeated units of mononucleotides.

Definition

Nucleic acids are the polymers of nucleotides. A nucleotide is a nucleoside containing phosphate group. A nucleoside is made up of a purine or pyrimidine nitrogenous base linked to a pentose sugar.

Classification : 

Nucleic acids are classified into

1. Deoxyribonucleic acids (DNA)

The most important consistuent of chromosome and exist as double stranded helix. The nitogenous bases present are adenine, guanine, cytosine and thymine and the pentose sugar is deoxyribose.

2. Ribonucleic acids (RNA)

RNA is a polymer of purine and pyrimidine ribonucleotides linked together by 3’, 5’ phosphodiester bridges. The nitrogenous bases are adenine, guanine, cytosine and uracil and the pentose sugar is ribose.

Types of RNA - There are 3 main classes of RNA molecules exist in all prokaryotic and eukaryotic organisms - They are messenger RNA (mRNA).

transfer RNA (t RNA)

ribosomal RNA (r RNA)

Functions of DNA

·           DNA serves as genetic material in cells.

·           DNA provides information inherited by the daughter cells and is also a source of information for the synthesis of proteins and it produces mRNA essential for protein biosynthesis.

Functions of RNA

·           It primarily functions in the cytoplasm of the cell as template for the synthesis of protein.

·           It carries genetic information from DNA to the site of protein biosynthesis.

·           It is an essential component of ribosome

·           Some RNA has enzymatic activity

·           It serves as genetic material for viruses such as tobacco mosaic virus, polio virus etc.