Human Genome Project
The Human Genome Project is an international scientific program to analyze the complete chemical instructions that control heredity in human beings. One complete set of these instructions is called a genome.
All living things contain hereditary instructions of the kind that researchers are analyzing in the Human Genome Project. 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). Experts were correct when they estimated that the human genome contained about 3 billion of these bases. The electronic files of each of the chromosome sequences totals more than 3,000,000,000 bytes.
Scientists are sharing information to determine the exact arrangement of bases in the genomes of living organisms. This process is called sequencing. Although bases can combine chemically in any order, they occur in almost the same order in all human beings or all the members of any other species. In any two human genomes, only about one base in one thousand differs.
In 1999, scientists completed sequencing of the human chromosome designated number 22. Scientists determined the order of over 33 million bases that make up over 700 genes on chromosome 22. This was the first of the 23 pairs of human chromosomes to be sequenced. In June 2000, the Human Genome Project and Celera Genomics Corporation, a private company, announced that together they had sequenced essentially the entire human genome. In 2001, American and British scientists used these findings to determine that the human genome has about 40,000 genes, far less than previously believed. The scientists also found that humans share many genes with such primitive organisms as bacteria.
Knowledge gained in the Human Genome Project may one day enable experts to analyze individual differences among genomes. (See Maynard V. Olson, "Human Genome Project," World Book Online Americas Edition, http://www.worldbookonline.com/wbol/wbPage/na/ar/co/266465, February 28, 2002.)
Because the complete sequence of a human chromosome requires a file in size of between 46 Megabytes to 285 Megabytes, we have only included 500 lines of the complete sequence of each chromosome.