dna microarray and its methodology

PRESENTATION ON:

AKANKSHA BISHT

B.TECH(BT)-5TH SEM

SUBMITTED BY:

BANASTHALI UNIVERSITY

SESSION:2016-17

DNA MICROARRAY

INTRODUCTION• DNA chip or biochip• Consists of a small glass

plate encased in plastic• Collection of microscopic

DNA spots attached to a solid surface

• Used to measure gene expression level

• Each spot contains multiple copies of a unique DNA sequence

Image retrieved from www.learn.genetics.utah.edu


• Investigating human genes one or few at a time…• Humans – around 20000 genes

In 20th century


Years passed…took a long time to investigate each gene

To learn about every gene in an organism in ONE SINGLE EXPERIMENT!

HISTORY• Evolved from southern blotting• 1995-Miniaturized Microarrays first reported• 1997- Microarray for a complete eukaryotic

genome

PRINCIPLE


GENE EXPRESSION

• Various types of cells in body are different from one another due to different genes being “turned on” and “turned off”.


METHODOLOGY OF MICROARRAY

COMPARING DIFFERENCES IN GENE EXPRESSION LEVELS IN HEALTHY CELLS AND CANCER CELLSIn cancer cells, Cell growth spin out of control


METHODOLOGY(contd.)

Healthy and Cancer tissue sample taken

• Tissue samples dissolved in organic solvent

• RNA extracted • DNA, proteins and other cell

components separated


METHODOLOGY(contd.)Mixing the tissue samples on the Vortex RNA will be released Samples are centrifuged to separate

RNA from rest of the cell components


METHODOLOGY(contd.)• After centrifugation, RNA separated from the rest• Then both samples pipetted out in different collection tubes


METHODOLOGY(contd.)

• RNA Samples washed over Columns filled with small beads

• These beads bind only to RNA strands with Poly-A tail

• Other molecules washed away

METHODOLOGY(contd.)

• Wash Buffer solution over beads• mRNA detached from the beads

Images retrieved from www.learn.genetics.utah.edu

METHODOLOGY(contd.)

• DNA copy of the RNA is made giving it some colour as labelling mix

• Green--Healthy cells RNA• Red --Cancer cells RNA

Images retrieved from www.learn.genetics.utah.edu

METHODOLOGY(contd.)

• Reverse transcriptase assembles labelled nucleotides into a cDNA molecule

• mRNA molecule degradedImages retrieved from www.learn.genetics.utah.edu

METHODOLOGY(contd.)

Both the Samples are spread on the MicroarrayImage retrieved from www.learn.genetics.utah.edu

METHODOLOGY(contd.)

• Microarray placed in washing solution• Extra cDNAs that didn’t bind to the

slide are washed off


METHODOLOGY(contd.)

HEALTHY CELLS• Many of the spots are Green but not every• Dark Spots are genes not transcribed in Healthy cells


METHODOLOGY(contd.)

CANCER CELLS• Red Spots pattern looks different• Skin Cancer cells and Healthy skin cells have different

gene expression pattern


METHODOLOGY(contd.)RED AND GREEN SPOTS MERGED TOGETHER• Yellow spot --gene

expressed both in healthy cells and cancer cells

• Yellow genes—No change in activity when cell becomes cancerous

• Red spots--genes “turned-on” in cancer cells producing more mRNA

• Green spots --genes “turned-off’ in cancer cells


APPLICATIONS• Gene Expression Profiling• Comparative Genomics Tool• Disease Diagnosis• Drug Discovery• Toxicological Research

Images retrieved from www.wikipedia.org

ADVANTAGES• Provides data for thousands of genes• One experiment instead of many• Huge step closer to discovering cures for

diseases • Different parts of DNA can be used to study

gene expression

DISADVANTAGES• DNA Chips are expensive to create• Production of too many results at a time

requires long time for analysis• DNA Chips do not have very long shelf life

CONCLUSION• One of the most effective invention ever

developed• Most powerful when used on species with

sequenced genome• Readily accessible, widely used technology to

investigate biological systems• Applications in wide array of biological

sciences

REFERENCESSOURCE:• Kumar R, Sharma A, Tiwari R.K. Application of Microarray in

Breast Cancer:An Overview. J Pharm Bioallied Sci. 2012 Jan 4(1):21-6.

• Trevino V, falciani F, Hugo A.B. DNA Microarrays: A Powerful Genomic Tool for biomedical and Clinical Research. MolMed, 2007. Vol. 13(9-10)

NET SOURCE:https://wikipedia.orghttps://www.genome.govhttps://www.learn.genetics.utah.edu

https://wikipedia.org/

https://www.genome.gov/

https://www.learn.genetics.utah.edu/

THANK YOU

dna microarray and its methodology

Technology