Human Genome Project, an international scientific program, helped analyze the chemical instructions that control heredity in human beings. One complete set of these instructions is called a genome << JEE nohm, >> . The Human Genome Project also analyzed the genomes of the house mouse, whose scientific name is Mus musculus; the fruit fly, known scientifically as Drosophilia melanogaster; and a roundworm called Caenorhabditis elegans.
The structure and importance of genomes.
All living things contain hereditary instructions in their cells. These instructions 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 (C), adenine (A), guanine (G), and thymine (T). A human genome contains about 3 billion of these bases, which cluster together in about 25,000 larger units called genes. Genes are arranged on 23 pairs of rod-shaped structures called chromosomes.
Scientists share information to determine the exact order of bases in the genomes of people and other living organisms. This process is called sequencing. Although bases can occur in any order, they exist in almost the same order in all human beings or all the members of any other species. In any two human genomes, only about 1 base in 1,000 differs.
These slight variations in genomes control the inherited aspects of traits that make people different from one another. For example, some variations produce differences in eye color, skin color, and blood type. Others contribute to differences in height and weight. Still other variations may significantly increase the likelihood that individuals will get a particular disease.
The work of the Human Genome Project
began formally in 1990. In 1998, scientists completed sequencing of the roundworm Caenorhabditis elegans. C. elegans was the first multicellular organism to have its entire genome sequenced. In 1999, researchers completed the first sequencing of a human chromosome, which was designated number 22. During the early 2000’s, the Human Genome Project and Celera Genomics Corporation, a private company, finished the sequencing of essentially the entire human genome. They thus located precisely where most human genes occur within the genome, providing a nearly complete human gene map.
Researchers used these findings to determine that a human genome has about 25,000 genes. Scientists also found that the sequences of many human genes closely resemble the sequences of corresponding genes in such simple organisms as worms, flies, and bacteria.
Future research.
The Human Genome Project officially ended in 2003. Yet researchers continue to use knowledge gained from this project. For example, the project’s genetic sequencing techniques have helped other scientists sequence the genomes of dogs, chimpanzees, and some other animals. Human Genome Project data are also helping experts determine various genes’ roles in normal body processes and in disease. Such work involves analyzing individual differences among genomes, and it may lead to effective disease treatments.
Many people, however, believe genome analyses could reveal health information that should remain private. Scientists and ethicists (people who address questions of right and wrong) are studying how to prevent the misuse of genetic information.
