DNA+Chips+by+Hanana+Marie+Shertick

What are DNA chips?
DNA chips are a collection of microscopic DNA spots attached to a solid surface. They consists of a few hundred to ten thousand types of DNA fragments which are densely placed on a glass or resin substrate. The DNA microchip is a new tool used to identify mutations in genes like BRCA1 and BRCA2. The chip is manufactured somewhat like a computer microchip. On the surface, each chip contains thousands of short, synthetic, single-stranded DNA sequences.

How they do they work?
Scientists use DNA microarrays to measure the expression levels of large numbers of genes simultaneously or to genotype multiple regions of a genome.


 * these are steps required in microarray experiment.

3 types of DNA chips

 * cDNA chips
 * A cDNA chip consists of a collection of cDNA fragments which are reverse transcripts of gene transcription products (mRNA). These cDNA fragments are immobilized on a substrate. The probes are the cDNA fragments previously adjusted according to the PCR method. A cDNA chip is produced by spotting the fragments on the substrate using a spotter. The lengths of cDNA are generally not uniform. Nucleic acid probes for detection can be spotted ranging from a few hundred nts (nucleotides) to over a thousand nts.
 * Oligo DNA chips
 * An oligo DNA chip is a DNA chip whose probe is the chemically synthesized oligo DNA after genes corresponding to exons in the region of 20-100 nts are selected. Since the probe is shorter than a cDNA chip, its specificity is high and cross hybridization can be inhibited.
 * BAC clone chips
 * A BAC clone chip is a DNA chip whose probe is a template amplified by PCR. The template is a genome region incorporated into a comprehensive BAC (bacterial artificial chromosome) clone which various research institutions used in decoding the genome sequence of various organisms. BAC is a vector that can clone a gene of 100-300 kb long. A BAC clone chip is used to analyze the number of genomic DNA copies in such methods as the CGH array.

What is it used for and why is it needed?
Because chip technology is still relatively new, it is currently only a research tool. Scientists use it to conduct large-scale population studies - for example, to determine how often individuals with a particular mutation actually develop breast cancer.

Better understanding of DNA chips
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DNA Chips Video
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DNA chips on T.V.
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