Nucleic Acid – Definition, Types, Structure, Functions and Properties
Definition of Nucleic Acid:
Nucleic acids are the polynucleotides having high molecular weight. The monomeric unit of which is nucleotide.
Types of Nucleic Acids:
1) Ribonucleic Acid (RNA)
2) Deoxyribonucleic acid (DNA)
1) RNA: May be found in nucleus but mainly occurs in cytoplasm carry out protein synthesis work.
2) DNA: Occurs in nucleus as well as cell organells like chloroplast and mitochondria.
Types of RNA:
1) Transfer RNA (t-RNA)
2) Messenger RNA (m-RNA)
3) Ribosomal RNA (r-RNA)
Structure of Nucleic Acids: Nucleic acid components:
Sugar – ribose or dexyribose
Base + sugar = Nucleoside – N – glycoside bond.
Nucleoside + phosphoric acid = Nucleotide – Ester bond.
Nucleic Acids – condensation polymer of nucleotide (Nucleotide – nucleotide) phosphor diester bond.
Watson -Crick double helical structure of DNA and forces responsible for stability of helix.
Functions of Nucleic Acids:
1) Transmission of hereditary Characters (DNA)
2) Synthesis of Proteins (RNA)
DNA: Store house of genetic information control protein synthesis in cell. Direct synthesis of RNA.
RNA: Direct synthesis of specific proteins.
m-RNA: To take genetic massage from RNA
t- RNA: Transfer the activated amino acids to the site of protein synthesis.
r-RNA: Function not clearly understood. Mostly present in ribosomes and responsible for stability of m-RNA.-
Properties of Nucleic Acid:
1) Optical Property: Absorbance in UV at 260 nm
2) Melting Temperature: Tm analysis