DNA MICROARRAY

BBAU LUCKNOWA PRESENTATION

ONDNA MICROARRAY

Submitted By:Rishabh GargM.Sc. IndustrialMicrobiology7895826925

INTRODUCTION Definition: DNA microarrays are

solid supports, usually of glass or silicon, upon which DNA is attached in an organized grid fashion. Each spot of DNA, called a probe, represents a single gene.

There are several synonyms of DNA microarrays such as DNA chips, gene chips, DNA arrays, gene arrays and biochips.

DNA Microarrays are one of the most effective invention ever developed. A DNA Microarray is a test that allows for the comparison of thousands of genes at once. Microarray technology uses chips with attached DNA sequences as probes for gene expression. Any DNA in the sample that is complementary to a probe sequence will become bound to the chip. Microarray technology is most powerful when it used on species with a sequenced genome. The microarray chip can hold sequences from every gene in the entire genome and the expression of every gene can be studied simultaneously. Gene expression data can provide information on the function of previously uncharacterized genes.

HISTORY Microarray technology evolved from

Southern blotting, where fragmented DNA is attached to a substrate and then probed with a known DNA sequence.

The use of miniaturized microarrays for gene expression profiling was first reported in 1995, and a complete eukaryotic genome (Saccharomyces cerevisiae) on a microarray was published in 1997.

PRINCIPLE The principle of DNA microarrays lies on

the hybridization between the nucleotide. Using this technology the presence of one genomic or cDNA sequence in 1,00,000 or more sequences can be screened in a single hybridization.

The property of complementary nucleic acid sequences is to specifically pair with each other by forming hydrogen bonds between complementary nucleotide base pairs.

Chip Mechanisms

TYPES There are 2 types of DNA

Chips/Microarrays:

cDNA Based Microarray Oligonucleotide Based Microarray

cDNA Based Microarray- This type of chips are prepared by using cDNA, it is called cDNA chips or cDNA microarray or probe DNA. The cDNAs are amplified by using PCR. Then these immobilized on a solid support made up of nylon filtre of glass slide (1 x 3 inches).

Oligonucleotide Based- In oligonucleotide microarrays, short DNA oligonucleotides are spotted onto the array. The main feature of oligonucleotide microarray is that each gene is normally represented by more than one probe: the ensemble of probes mapping to different regions of the gene is usually called probe set. Commercial oligonucleotide chips are available (e.g. Affymetrix, Inc. GeneChip system)

APPLICATIONS The DNA chips are used in many areas as given

below:

Gene expression profiling Discovery of drugs Diagnostics and genetic engineering Alternative splicing detection Proteomics Functional genomics DNA sequencing Toxicological research (Toxicogenomics)

ADVANTAGES Provides data for thousands of genes.

One experiment instead of many.

Fast and easy to obtain results.

Huge step closer to discovering cures for diseases and cancer. Different parts of DNA can be used to study gene expresion.

DISADVANTAGES• The biggest disadvantage of DNA chips

is that they are expensive to create.• The production of too many results at a

time requires long time for analysis, which is quite complex in nature.

• The DNA chips do not have very long shelf life, which proves to be another major disadvantage of the technology.

REFERENCE http://www.highveld.com/molecular-biolo

gy/oligonucleotide-microarrays.html https://en.wikipedia.org/wiki/DNA_microar

ray Lehninger, 2005, DNA Chips, Principle of

Biochemistry, W.H. Freeman and Company, Newyork, forth Edition, Pg. 326- 328

Presscot M. Lansing, 2002, DNA Chips, Microbiology, Athenaeum Press Ltd, Gateshead, Tyne and Wear, Britain, Fifth Edition, 353 – 354.

THANK YOU !