DNA microarray other name DNA chip or biochip

DNA Microarray

“By being able to see… all the genes, all the genetic variation, we can readily pick out answers.” by Eric Lender {A Human Genome Project Leader}

DNA microarray also known as DNA chip or biochip. DNA microarray is a collection of microscopic DNA spots attached to a solid surface. Scientists use DNA microarrays to measure the expression levels of large numbers of genes simultaneously or to genotype multiple regions of a genome.  Each DNA spot contains picomoles (10−12 moles) of a specific DNA sequence, known as probes or reporters or oligos.

There are about 30,000 different genes in human DNA. Different cells in the body although having identical DNA, switch on and off different genes, depending on what is needed to build that particular cell. Studying which genes are active in a cell is a useful way to find out what makes it function and helps identify what has gone wrong when it is not functioning properly.

In 1989 U.S. scientist Stephen Fodor presented a technique that was to revolutions DNA analysis. He created a DNA microarray-a glass slide with up to 500,000 different stands of DNA attached to it. When a gene is switched on in a cell, a complimentary copy of that gene’s information (called messenger ribonucleic acid or mRNA) is produced by the cell. This is like a mirror image of a particular stretch of DNA. Matching pieces of mRNA and DNA will stick together. To find the active genes a cell is treated with a dye that attaches itself to mRNA and then the cell contents are added to the microarray. The mRNA stands will stick to any matching DNA sequences and the dye will show them up. The microarray has already proved to be powerful tool for learning about many different illnesses from heart disease to cancer.