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micro array

A semiconductor device that is used to detect the DNA makeup of a human cell. DNA chains comprise molecules that pair with each other, and micro arrays contain millions of DNA strands designed to mate with their other half as the liquefied human cells are poured over them. This "hybridization" process is then detectable by a laser.

Micro arrays are revolutionizing medicine by being able to pinpoint a very specific disease or the susceptibility to it. Sometimes called "biochips," Affymetrix (www.affymetrix.com) pioneered this technology with its GeneChip family. See Human Genome Project.




Micro Array Features
The square locations on this Affymetrix array are called "features," and each feature holds millions of identical DNA strands called "probes." The probes are built like semiconductor chips, one layer at a time. (Image courtesy of Affymetrix.)






Hybridization (Pairing)
The human DNA sample, which has been replicated millions of times and fragmented into short pieces, is washed over the micro array. The red balls depict biotin molecules that were adhered to the fragments, which "swim" around the probes for up to 16 hours. During that time, some strands will pair with the probes (the hybridization process). (Image courtesy of Affymetrix.)






Detection
The array is rinsed and washed with a fluorescent stain that clings to the biotin on the strands of the human sample that remain. A laser causes them to glow, and the DNA is analyzed (genotyped) based on which probes on the array they mated with. (Images courtesy of Affymetrix.)






Human Genome Project

A bioinformatics project that has identified the 30,000 genes in human DNA. Coordinated by the U.S. Department of Energy and the National Institutes of Health, the U.S. Human Genome Project started in 1990 and released its findings in February 2001 along with findings from a separate project by Celera Genomics Group. There are similar projects in other countries as well. The purpose is to store the three billion chemical base pairs (the DNA sequence) derived from these analyses in databases for use in biomedical research. See micro array.

The End Goal
The goal of the Human Genome Project is to determine the relationships between DNA makeup and human traits and predispositions. Although sequencing costs have been extremely expensive, they are approaching the USD $1,000 level per human genome, enabling "personalized genomics" to dramatically alter the course of medicine. See Personal Genome Project.

A Human Component Dictionary
This information is not a blueprint of the human being, rather it is a dictionary of components. Once believed that each gene made only one protein, it is now believed that each gene creates numerous proteins, although this information is expected to take years to determine. Part of the U.S. government project is to study the ethical and legal impact that this information will have on society. An abundance of information can be found at www.genome.gov.



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