SCIENCE IN THE NEWS #2076 - Human Gene Map

By George GrowThis is Steve Ember.And this is Bob Doughty with SCIENCE IN THE NEWS, a VOA Special English program about recent developments in science. Today we tell about a major effort by scientists to map the position of every human gene.

Scientists in the United States and other countries have been working to produce a map of human genetic material, commonly known as DNA. The letters DNA represent deoxyribonucleic acid. Every cell of every living thing contains DNA. Scientists call it the chemical of life. All of the DNA in the cells is called the genome.

Finishing this map would be an extremely important discovery. It would describe a person's complete genetic structure. This structure includes more than three-thousand-million chemical pieces linked together.This information decides a person's physical appearance, such as hair color, eye color and height. The genetic information also may make a person more likely to develop some kinds of cancer or other diseases.

Completion of the human genetic map will help scientists study the mysteries of human health and disease. The discovery is expected to change the way some diseases are treated. It would help doctors develop new treatments that fight disease on the level of cells and genes.Scientists knew that DNA existed long before they could describe its shape. The structure of genetic material was discovered in Nineteen-Fifty-Three. American scientist Jim Watson and British scientist Francis Crick made the discovery. They found that each molecule of DNA looks like a twisted ladder called a double helix.

DNA is made up of genes. Genes, like letters in words, carry a huge amount of information. These messages tell cells how to make all the materials for life.Genes are carried on chromosomes. Almost all human cells have forty-six chromosomes. There are hundreds of genes on each chromosome. The chemicals that make up DNA are nucleic acids. There are four kinds of nucleic acid: adenine, thymine, guanine and cytosine. These chemicals are called bases. They are represented by the letters A, T, G and C. Scientists say human chromosomes have about three-thousand-million pairs of these bases.

Some teams of scientists have independently identified the structure of many individual genes. However, there is no map that shows every gene on every chromosome. That is the goal of the Human Genome Project - to map the exact chemical order of the DNA in every cell of the human body.

((MUSIC BRIDGE))The Human Genome Project was first proposed in the Nineteen-Eighties. The project was widely discussed within the scientific community and by the press. By Nineteen-Eighty-Eight, two American government agencies were working together to organize research studies and other activities connected with the project.

Ten years ago, the United States Congress agreed to provide financial support for the Human Genome Project. In the first few years, progress seemed very slow. Leaders of the project promised a complete gene map by Two-Thousand-Five.Two years ago, the international scientific community was surprised when a small American company announced that it would organize a major effort to make the gene map. Research scientist Craig Venter was named to head the company, Celera Genomics. The company is based in Rockville, Maryland, near Washington, DC.

The announcement led immediately to a dispute among the top scientists in the country. No one expected a small group of scientists to compete against the Human Genome Project.

Some people said the competition has helped to speed the rate of research. Supporters of the Human Genome Project agreed to increase financial support for the project. They are investing an estimated two-hundred-fifty-million dollars to produce a first version of a map of every chromosome.About one-thousand scientists are now working together on the Human Genome Project. They are based in the United States, Britain, China, France, Germany and Japan.

Major improvements in technology have increased the speed of producing the genetic map. For example, the Human Genome Project identifies twelve-thousand chemical bases every minute. Three years ago, identifying that many bases would have required twenty minutes. Twenty years ago, the same identification would have required one year or more.The two groups of scientists are using different methods to produce the gene map. The government-supported Human Genome Project followed a slower, more conservative program. Scientists made maps of large parts of the genetic material. They divided the material into smaller pieces for additional study. Later, the pieces were put together in the order they appear on the chromosome.

Scientists at Celera Genomics are using another method. First they broke the DNA into millions of pieces. Then powerful computers examined this information and put the pieces together. Next, the scientists collected and combined their findings.Francis Collins heads the Human Genome Project. Doctor Collins says he believes his group has finished about ninety percent of the genetic work. It is expected to announce early results by the end of this month. The government-led scientists have shared their research findings on the Internet computer system.

Earlier, experts had criticized Celera Genomics for wanting property rights to information provided by the government group. However, Celera now says it will put most of its information on the Internet when its studies are completed.

((MUSIC BRIDGE))Competition between the two groups has led to the announcement of a series of genetic discoveries. Late last year, scientists with the Human Genome Project reported that they had made a map of a human chromosome for the first time. The scientists identified almost every chemical structure on Chromosome Twenty-Two. It is one of the smallest chromosomes.

Scientists believe about thirty-five disorders are caused by genes on Chromosome Twenty-Two. They include some forms of heart disease, birth defects, several kinds of cancer and the mental disorder schizophrenia.

About the same time, scientists at Celera Genomics reported the discovery of what they call the smallest number of genes necessary for a cell to live and copy itself. Craig Venter says his group found that three-hundred genes are necessary for life. The scientists say this knowledge could lead to creating a living organism in the laboratory.Earlier this year, Celera reported its scientists had produced a genetic map of the common fruit fly. The insect is the most complex organism to have all of its genetic structure identified. A computer study suggests the fruit fly has about thirteen-thousand-six-hundred genes. The scientists were surprised to discover the large number of fly genes that are similar to human genes. By studying the insect, scientists hope to learn how these genes work in humans.

In April, Celera announced it had identified all the chemical pieces of human DNA. One week later, scientists at the Department of Energy said they had identified the structure of three human chromosomes. They said this represents about eleven percent of all human genes.Scientists disagree about how many genes humans have. However, government scientists believe humans have between fifty-thousand and one-hundred-thousand genes.

Researchers are expected to announce soon that they have completed a map of all the human genes. The map will provide a description of the structure of human genetic material. However, it will only show the general structure of the genes. The real work will involve identifying and understanding all of this information. Scientists say it will be years before the genetic map is fully understood.

This SCIENCE IN THE NEWS program was written by George Grow. This is Steve Ember.And this is Bob Doughty. Join us again next week for more news about science in Special English on the Voice of America.

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