Human Genome Project, JEE nohm, is an international scientific program to analyze the complete chemical instructions that control heredity in human beings and certain other organisms. All living things contain such instructions, which are carried on long coils of a chemical called DNA (deoxyribonucleic acid). DNA contains four types of simpler chemicals called bases. The four types of bases are cytosine, adenine, guanine, and thymine. Scientists estimate that the human genome--that is, one complete set of instructions--contains about 3 billion bases.

Scientists worldwide are sharing information to determine the exact order in which these bases occur. Scientists hope that identifying the order of bases in the human genome will lead to development of highly detailed gene maps. These maps will show where each gene lies on a chromosome and reveal each gene's role in normal body processes or disease.

The Human Genome Project began formally in 1990. Knowledge gained in the project may someday enable scientists to analyze an individual's genome. Because genetic variations cause or contribute to certain diseases, analysis of a person's genome could reveal health information that should remain private. Scientists in the project are studying how to protect people from misuse of such information.

Excerpt from the "Human Genome Project" article, The World Book Encyclopedia © 1999