The genetic material is stored in the form of DNA in most organisms. In humans, the nucleus of each cell contains 3 × 109 base pairs of DNA distributed over 23 pairs of chromosomes, and each cell has two copies of the genetic material. This is known collectively as the human genome. The human genome contains around 30 000 genes, each of which codes for one protein.
Large stretches of DNA in the human genome are transcribed but do not code for proteins. These regions are called introns and make up around 95% of the genome. The nucleotide sequence of the human genome is now known to a reasonable degree of accuracy but we do not yet understand why so much of it is non-coding. Some of this non-coding DNA controls gene expression but the purpose of much of it is not yet understood. This is a fascinating subject that is certain to advance rapidly over the next few years.Explanation: hope this little pargraph helps :D
