Deoxyribonucleic acid (DNA) is nature's storehouse of coded information that controls development and functioning of all living organisms. DNA can also be described as the ultimate coded message that continues to baffle scientists. It has a very complex structure because it is composed of millions of units. Yet, it is simple because it is built of only four basic units or bases: adenine, guanine, cytosine, and thymine. Long strands of DNA are built on a backbone of sugar and phosphate molecules using these four bases as building blocks. Two complementary strands are joined together in the dorm of a double helix. The double helix structure of DNA was discovered by James Watson, Francis Crick, and Maurice Wilkins in 1953 for which they were awarded the Nobel Prize.
Most of the DNA in larger organisms resides in chromosomes found in the nucleii of cells that make up various organs and tissues. Human beings have 23 pairs of chromosomes. All these choromosomes collectively are referred to as the human genome. The human genome contains more than three billion bases. Scientists have long believed that if they could determine the exact sequence of all bases in the human genome, they will be able to identify causes of a variety of human diseases and find cures for the same. However, the task of determing the exact sequence of billions of bases was so huge that no single individual could attmept to undertake this task. The Human Genome Project was initiated in the early 1990s with the objective of mapping the entire human genome. It was supported by the the governments of the United States and other countries and the work was carried out in various universities. A private corporation also invested its money to map the human genome. The task of mapping the entire genome was completed in 2003 and the two teams simultaneously published their initial reports. In a historical move, the two teams reached an agreement under which they agreed to make the sequence available to anyone for free for the benefit of mankind. It was hoped that this knowledge will trigger the development of innovative treatments for human ailments.
An interesting aspect of the human genome is that it is estimated to contain approximately 30,000 genes. However, these genes represent a very small part of the DNA contained in the genome. Scientists do not know anything about the information contained in the rest of the genome and how it is used. It is also known that there is a significant amount of overlap between the genome of human beings and that of other organisms.