What is DNA?

Deoxyribo Nucleic Acid(DNA)

Watson and crick established the structure of DNA molecule in 1953 on the base of x-ray diffraction. For this excellent discovery, Watson and Crick was awarded with the Nobel Prize.According to them, DNA is a composed of two antiparallel polynucleotide chains that form a double helix around the central axis.

            The strands are made up of alternate bonds of deoxyribose sugar and phosphate moelucles. They are joined together by the phosphodiester linkages.

            Each deosxyribose sugar has one N-base horizantally attached to it at carbon-1. The four N-bases occur in any possible sequence along the length of a strand.The N-base + deoxyribose sugar + phosphate together form one unit or deoxyribonucleotide in the strand. Such many deoxyribosenucleotides are linked with each other in a liner fashion, therefore, the resulting strand is described as the polynucleotide strand and DNA molecule as polunucleotide chain.

            The two strands of helix are of opposite polarity. If one chain runs in 3’-5’ direction (sugar phosphate linkage), then the other will run in 5’-3’ direction (sugar-phosphate linkagae).

FUNCTIONS:

1)    DNA is a genetic material, hence it carries all the heredity inforamtion from one generation to another generation.

2)    DNA has unique properties of formation of exact copies. This is essential for transfer of genetic information.

3)    DNA gives rise to RNA through transcription process.

4)    DNA plays a key role in protein synthesis.

5)      Any change in the sequence of nitrogen bases of DNA causes mutation.