SNPs, Chips, and the essays

SNPs, Chips, and the essays Single nucleotide polymorphisms (SNPs) are DNA sequence variations that occur when a single nucleotide is altered. A SNP might change the DNA sequence from AAGGCTAA ATGGCTAA. SNPs occur every 100 to 300 bases. SNPs can occur in both coding and noncoding regions of the genome. Some SNPs have no effect on cell function, but others can have a major impact on how humans respond to disease and drug therapies. This makes SNPs of great value for biomedical research and for developing pharmaceutical products. SNPs also do not change much through generations, making them easier to follow in population studies. Scientists believe SNP maps will help them identify the genes (there are many genes involved) associated with such diseases as cancer, diabetes, and some forms of mental illness. SNP maps are also expected to identify thousands of additional markers along the genome. Over the past several years, a new technology called DNA microarray has attracted enormous interest among scientists. A microarray is a tool for analyzing gene expression that consists of a small membrane or glass slide containing samples of many genes arranged in a regular pattern. This technology can monitor an entire genome on a single chip so that researchers can have a better picture of the interactions among thousands of genes. Microarrays may be used to assay gene expression within a single sample or to compare gene expression in two different cell types or tissue samples, such as in healthy and diseased tissue. Only a fraction of an organisms genes are turned on. It is the genes that are turned on, or expressed, that gives the distinctive properties to each cell type. A microarray works by allowing mRNA molecules to hybridize to the DNA template from which it originated. By using an array containing many DNA samples, scientists can determine the expression levels of hundred s or thousands of genes within a cell by measuring the a...