What
Why Is the Human Genome Project Studying It?
September 1998
http://www.nhgri.nih.gov/NEWS/Finish_sequencing_early/what_is_DNA.html
What Is DNA?
All the information needed to form and sustain life is contained in the molecule deoxyribonucleic acid, or DNA. All living creatures, from bacteria, viruses, and fungi, to plants, animals and humans use this universal instruction language. In humans, a sperm and an egg join forces to assemble the unique instruction booklet for the newly forming embryo. DNA directs the formation of every single cell in the body from conception to death, and coordinates all functions of every organ system, every tissue, every cell, and every molecule. From the moment of conception, many physical traits such as eye and hair color are spelled out by DNA. It is therefore the molecule by which children inherit traits from their parents.
For all the complexity of life, this compound is deceptively simple in structure. DNA is composed of four chemical bases. The letters A (adenine), T (thymine), C (cytosine), and G (guanine) designate the chemical names of the bases. These bases line up to form slender strands. These long strands associate together in pairs that coil around each other to resemble a twisted ladder. Within the tiny cell nucleus, each long twisted ladder is folded compactly around other molecules, and is called a chromosome. In humans, 23 pairs of these microscopic chromosomes reside in the nucleus of each of the trillions of cells in the body. Collectively, these 23 pairs of chromosomes are called the human genome.
When a cell divides and new cells are formed, DNA copies itself in a process called replication. When this process is complete, there are two twisted ladder structures where there had been one, and the newly formed cell has its own complete genome.
Each person’s DNA sequence contains their genetic instructions, the information that directs all their biological processes. Ninety-nine point nine percent of the DNA between two individuals is identical. But certain variations in a person’s DNA may cause him or her to develop a genetic illness or to be susceptible to a disease. By deciphering the sequence of human DNA, scientists will gain new insights into how DNA misspellings cause these illnesses, thereby allowing them to develop better treatments and even cures.
How Does DNA Carry Out Its Job?
How do these tiny strings of bases instruct all the complicated biological processes of the body? Along the chromosomes, groups of base pairs called genes team up to carry out specific jobs. A single gene typically consists of several thousand bases. There are an estimated 60,000-100,000 genes in the human genome.
When a gene moves into action, the twisted DNA strands of a chromosome separate in the area of the active gene, and a new molecule is synthesized, using the DNA as a template. This new molecule, which is a chemical cousin to DNA, is called RNA (ribonucleic acid). The newly formed RNA detaches from the DNA strand, and acts as a template for the final products—proteins, essential components in all living cells.
How long does it take for a gene to make a protein? Imagine you were eating a chocolate bar when you began reading about DNA. In the time it took you to read to this point, the DNA in a region of chromosome 11 in the cells of your pancreas, a digestive organ, uncoiled and synthesized RNA from the insulin gene. The RNA was processed, and the insulin protein was manufactured, modified, folded, and secreted into your bloodstream, where it will help triage the sugar from the chocolate bar. Your body also is synthesizing a fleet of other proteins to further process, store, or ferry the energy derived from the sugar to an area of high activity such as your brain, as you "digest" what you just read.
Why Is the Human Genome Project Studying DNA?
The likelihood of developing a heritable disease is spelled out in a person’s DNA. A variation in DNA that predisposes to illness may exist from birth, or may be acquired during the course of one’s life through such effects as radiation exposure. Also, throughout life DNA will copy itself and direct protein synthesis countless times, and occasionally mistakes occur. Sometimes the body is unable to repair these mistakes and the result may be a disease, such as certain forms of cancer. Although alterations in the spelling of our DNA may cause disease, environmental factors, such as choosing a healthy lifestyle, often affects the likelihood of developing disease. Knowing one is at risk for a particular illness often can allow that risk to be reduced, by lifestyle changes or medical surveillance.
Knowledge of the sequence of human DNA will allow scientists to identify and understand the function of human genes. From there, researchers can begin to unravel biology’s most complicated processes, including the cause of many human diseases. Already as a result of the HGP, new disease genes are discovered almost weekly. Recent successes include genes for colon cancer, breast cancer, diabetes, and Alzheimer’s disease. When scientists identify a disease gene, they can begin to understand the illness at a molecular level, and therefore over time can develop the best strategies for treatments and even cures.
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Data Release and Access Principles and Policy
The human genome, the common heritage of all humanity, is arguably the most valuable dataset the biomedical research community has ever known. It holds long-sought secrets of human development, physiology, and medicine.
The highest priority of the International Human Genome Sequencing Consortium is ensuring that sequencing data from the human genome is available to the world's scientists rapidly, freely and without restriction.
Since the sequencing phase of the Human Genome Project (HGP) began five years ago, all of the data generated by participants has been deposited in publicly available databases every 24 hours.
http://www.ncbi.nlm.nih.gov/Genbank/
http://www.ebi.ac.uk/embl/index.html
http://www.ddbj.nig.ac.jp/
Translating the text of the human genome into practical applications that will alleviate suffering is one of the greatest challenges facing humankind. This mission will require the work of tens of thousands of scientists throughout the world. No scientist wanting to advance this cause should be denied the opportunity to do so for lack of access to raw genomic data. Delaying the release of either unfinished or finished genomic DNA sequence data serves no scientific or societal purpose.