A so-called gene chip is actually a silicon or glass slide to which DNA is bound. The glass slide has an inherent adhesiveness for DNA that is enhanced with a coating of polyly-sine or saline. DNA is "spotted" on the glass under precise positional control using specialized equipment. Photolithographic DNA synthesis has enabled the large-scale production of GeneChip probe arrays containing hundreds of thousands of oligonucleotide sequences on a glass "chip"
about 1.5 cm2 in size. Up to 400,000 distinct sequences can be placed on one slide. The manufacturing process integrates solid-phase photochemical oligonucleotide synthesis with lithographic techniques similar to those used in the microelectronics industry. Because of their very high information content, GeneChip probe arrays are finding widespread use in the hybridization-based detection and analysis of mutations and polymorphisms ("genotyping"), and in a wide range of gene expression studies. Commercial chips can be purchased; alternatively, with the appropriate equipment, the laboratory can manufacture chips to its own specifications. Some of the commercial chips contain multiple copies of the same oligonucleotide, and this arrangement can enhance the validity of the obtained result.
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.