(25) DNA

         (29) Structure of a nucleotide

              (30) Nitrogen bases

       (23) Arrangement of the nitrogen bases

     The nucleus of every single cell contains deoxyribonucleic acid, or DNA. It is the most important molecule found in our bodies because it stores the information that direct protein synthesis. Furthermore, it governs the reproduction and growth of cells, thus ensuring the proper functioning of our organism. DNA also contains the genetic material that is the crucial source for heredity (15, 16, 27, 32). The scientists have discovered that deoxyribonucleic acid is the only existing molecule that is capable of reproducing itself through replication - enabling the continuity of life (16, 32).



     DNA is composed of monomers called nucleotides. Each nucleotide is made up of a phosphate group, a five-carbon sugar unit, and a nitrogen base. The sugar unit in the nucleotides of DNA is a monosaccharide known as deoxyribose. The nitrogen bases may be any one of four compounds – adenine (A), guanine (G), thymine (T), and cytosine (C) (15, 16, 28, 31).




     DNA is often described as a double helix that resembles a twisted ladder. The backbone of the ladder is composed of phosphate and sugar molecules, while the rungs are made up of nitrogen bases (16, 28). The two DNA strands are held together by many hydrogen bonds – with two hydrogen bonds connecting each thymine (T) and adenine (A) and three bonds between each cytosine (C) and guanine (G) (15,16).