Deoxyribonucleic acid, more commonly known as DNA, is a complex molecule storing all the information about an organism and being used to reproduce and maintain the organism. Most part of DNA is used for structural maintenance, while some parts are used for storing genetic information, and others in regulating the expression of genetic information as amino acids and protein molecules. DNA does not interact directly with other molecules. Rather, various enzymes act on DNA to extract information from it. A portion of DNA is passed on to the offspring as the continuation of traits of the hereditary source.
DNA is about two metres in length. Each DNA is wound around proteins called Histones into ‘X’ shaped chromosome. As such humans have 44 informational chromosomes (DNA) and two sex chromosomes (DNA). Chromosome 1 is the largest and contains around 8,000 genes. The smallest is chromosome 21 with around 3,000 genes.