Nucleic Acids

Nucleic acids are found in all living cells. they are composed of strands make up of repeating units called nucleotides. Each nucleotide consist of

• a five carbon sugar, 

• a phosphate group, and 

• an organic nitrogen containing base: adenine, guanine cytosine or thymine.

The repeating nucleotides are linked to form a sugar phosphate backbone with a base attached as a side arm to each sugar molecule.

     There are two types of nucleic acids:

• deoxyribonucleic acid or DNA in which the sugar is deoxyribose, and 

• ribonucleic acid or RNA in which the sugar is ribose. 

DNA : Deoxyribonucleic acid is found in chromosomes located in the nucleus of cells. It stores the organisms hereditary traits and directs the day to day metabolic activities of each cell in the organism. It can replicate itself during cell division and is the only material that is passed on from parent to offspring.

    The DNA molecule consist of two strands that carve spirally to form a double helix structure. The strands are held together by hydrogen bonds between the base side arms. Each base on one strand will only pair with a specific base on the other strand: hence guanine will only pair with cytosine and adenine with thymine. Thus , the sequence of bases on one strand is complementary to the order in the other strand. The blueprint of the organism is encoded in the sequence of bases in DNA.

RNA : Ribonucleic acid is similar to DNA except that it occurs as a single strand consisting of ribose sugars instead of deoxyribose sugars. RNA exists in three forms of varying lengths, all found in living cells. The basic function of RNA in cells is to carry out the synthesis of proteins under the influence of DNA.