Biochemistry - Nucleic Acid for dmlt and paramedical students

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

Ismail- Bio-chemistry