What is a genome?
The genome contains all the genes that are necessary to build and copy living beings. It is made of deoxyribose nucleic acid (DNA) – the famous double helix-shaped molecule – whose structure was discovered by Francis Crick and James Watson in the Cavendish Labs in Cambridge, England in 1953. The DNA is packed into long, dense fibres called chromosomes. Only about 3 per cent of the genome contains genes that encode for the RNA and proteins. The remaining 97 per cent of the genome contains `control regions’. These include the switching systems which tell genes when to switch on or off. Rest of the genome is packed with DNA about whose function scientists have little clue today, and is also called `junk DNA’.
A genome is an organism’s complete set of deoxyribonucleic acid (DNA), a chemical compound that contains the genetic instructions needed to develop and direct the activities of every organism. DNA molecules are made of two twisting, paired strands. Each strand is made of four chemical units, called nucleotide bases. The bases are adenine (A), thymine (T), guanine (G) and cytosine (C). Bases on opposite strands pair specifically; an A always pairs with a T, and a C always with a G. The human genome contains approximately 3 billion of these base pairs, which reside in the 23 pairs of chromosomes within the nucleus of all our cells. Each chromosome contains hundreds to thousands of genes, which carry the instructions for making proteins. Each of the estimated 30,000 genes in the human genome makes an average of three proteins.
