The Human Genome Project

About 5 pages (1,393 words)

Human Genome Project Summary

Know this topic well? Help others and get FREE products!

The Human Genome Project

Overview

The Human Genome Project is a massive scientific effort to identify all human genes and determine the sequence of the chemical bases (nucleotides) of the entire human genome. The human genome has perhaps 50,000-100,000 genes, which are constructed from about 3 billion base pairs of nucleotides. There are four different nucleotides—adenine, cytosine, guanine, and thymine—and the arrangement of these four bases in specific sequences acts as a hereditary code. These 3 billion nucleotides are located on DNA molecules within 23 pairs of human chromosomes in the nucleus of cells in the human body. The Human Genome Project began in 1990 and was funded at $200 million per year by the United States National Institute of Health and the Department of Energy. At its inception it was expected to last 15 years and cost $3 billion, making it one of the largest single scientific projects funded by the United States government.

Background

In 1900 the experiments on heredity by the Austrian monk Gregor Mendel (1822-1884) were rediscovered, giving rise to Mendelian genetics. About the same time biologists discovered that the chromosome is the part of the cell involved in passing on heredity. The field of genetics took a great leap forward in 1953 with the discovery of the double helix model for DNA—the molecule in the chromosome responsible for transmitting genetic information from one generation to the next—by James Watson (1928- ) and Francis Crick (1916- ). This capped a long search by biologists for the chemical basis for heredity. It also opened up exciting new vistas for research into the nature of heredity and hereditary illnesses.

Impetus to begin the Human Genome Project came largely from health professionals who believed that the knowledge gained through the project could dramatically improve diagnosis and treatment of a wide range of genetic illnesses. For the past couple of decades, medical geneticists have been searching for various genes that cause major illnesses and have already identified some. In 1987, for example, a major breakthrough came when the gene causing cystic fibrosis was discovered. Finding the specificgene behind a particular illness cannot only greatly improve diagnosis—even in advance of the onset of the disease—but can also help scientists understand the root causes of the disease.

In 1987 the Department of Energy's Biological and Environmental Research Advisory Committee recommended the implementation of a large-scale research project to map the entire human genome. The Department of Energy had already funded research on the effects of various kinds of radiation on human health, and it had a good track record of managing large scientific research projects. The following year the National Research Council issued its own recommendation that the United States government, specifically the National Institute of Health, take the lead in human gene sequencing. To further this research, three national genome research centers were established in 1998-99 at Lawrence Berkeley National Laboratory, Lawrence Livermore National Laboratory, and Los Alamos National Laboratory.

In 1990 the project officially began, and James Watson, co-discoverer of the double helix model for DNA in 1953, became the first director of the National Center for Human Genome Research (its name changed to National Human Genome Research Institute in 1997). After Watson resigned in 1992, Francis Collins, a leading genetics researcher at the University of Michigan, took over leadership of the project in 1993.

The actual gene sequencing is being carried out at many different research centers in the United States, Japan, England, France, Germany, and China. Research teams at these various sites work on sequencing a discrete segment of a chromosome, and the results are synthesized. In addition to working on mapping and sequencing the human genome, part of the project include sequencing other organisms, partly to gain experience and refine research techniques. These include several microorganisms, the fruit fly, and the mouse. The latter two organisms have been two of the most important organisms used by scientists for research in genetics. The data from these organisms can provide useful comparisons between human heredity and the heredity of other animals. In 1995 the first whole genome for an organism other than a virus was sequenced when scientists completed sequencing the genome of a relatively simple bacterium, Haemophilus influenzae. By sequencing the microorganism Methanococcus jannaschii, scientists confirmed in 1996 that it belongs to a third major branch of life called Archaea (the other two are prokaryotes [bacteria] and eukaryotes [most other organisms]).

Producing physical maps of chromosomes involves cutting the DNA molecules using restriction enzymes—special chemicals that slice DNA at specific locations. Once the DNA molecule is cut into fragments, the fragments are cloned or copied. When enough overlapping DNA fragments are analyzed, maps of the chromosomes can be constructed. Maps are the first step in sequencing all the nucleotides in the DNA. Data obtained from the sequencing projects is stored in the Genome Database, established in 1991 at Johns Hopkins University. Because data are made available over the Internet, scientists throughout the world can take advantage of the information as soon as it is processed.

Impact

With the information generated by the Human Genome Project, scientists hope to be able to locate the genes that cause specific illnesses, as well as those responsible for normal functions. By knowing the nucleotide sequences they can figure out the ultimate physical basis for hereditary illnesses and for normal growth and development. Geneticists hope that this will not only aid diagnosis, but will ultimately lead to new treatments for genetic illnesses. While this aspect of the Human Genome Project is relatively unremarkable, more controversial is the possibility of using the information for genetic engineering. Treatments that involve manipulating the DNA are already being used on some illnesses, and such methods will likely increase as our understanding of human genetics expands.

The Human Genome Project has aroused many ethical concerns. The concerns were so pronounced that 5% of the project's budget was set aside to fund discussion of the ethical, social, and legal implications of the projected knowledge. This makes the project the first large scientific project to address the ethical dimensions of the knowledge generated. Some fear the Human Genome Project may presage "designer genes" and may mark the advent of a reinvigorated eugenics (conscious attempts to "improve" human heredity).

However, the most persistent concern seems to be privacy of information. Once we have the knowledge to locate many hereditary illnesses, perhaps years before they manifest themselves, how will we use this knowledge? Could knowledge about one's genetic makeup be passed on toinsurance companies, employers, or prospective mates? There seems to be broad agreement that people should have right to privacy regarding their own genetic makeup. The Human Genome Project's Ethical, Legal, and Social Issues branch in 1994 drafted legislation, the Genetic Privacy Act, to protect people against the misuse of genetic information, though Congress has not yet enacted it (as of late 1999).

As of December 1999, the Human Genome Project was ahead of schedule, partly because of advances in technology and sequencing techniques. It had already completed sequencing 15% of the human genome and also had some more in draft form. At the same time the project announced the completion of sequencing the first full human chromosome—chromosome 22. This chromosome consists of 33.5 million nucleotides and has at least 545 genes (scientists estimate there may be another 200-300 that are still not identified). The mean size of the genes on this chromosome is 190,000 nucleotides. Despite this remarkable accomplishment, there are still some gaps in the sequencing that present technology is unable to fill in, but even the gaps are identified.

HGP anticipates completing the rough draft of the entire genome in spring 2000 and completing the entire project sometime in 2003. However, a commercial competitor, Celera Genomics, was formed in 1998, and is racing to beat the Human Genome Project. Celera uses less precise sequencing methods, but boasts that its methods are faster and will produce a complete sequence of the genome by 2001.