DNA microarray is two dimensionally arranged series of DNA oligonucleotides also known as probes on solid surface like glass slide or silicone thin film used to study gene expression in different cells. The probes such as cDNA or cRNA attached via surface engineering to solid surface like glass slide or silicone chip.
Technology Involved in DNA Microarray:
1. DNA microarray is prepared using robotic machines that arrange hundreds and thousands of gene sequences (probes) on a single microscopic slide.
2. To determine which genes are active in a cell, researcher should collect all the mRNA from that cell. When a gene is active, cell machinery prepares template for protein production they are known as mRNA. These mRNA are complimentary to the active gene (DNA). Therefore will bind to the original DNA strand.
3. mRNA are then labelled with florescent dye.
4. Researches add these labelled mRNA into the DNA microarray slide.
5. mRNA that was present in the cell will bind to its complimentary DNA probes .
6. Hybridized mRNA gives out fluorescent signal, which can be measured using special scanners.
7. Genes (DNA) which is very active will produce many number of mRNA so will generate bright fluorescent area. Genes that are little active will produce less number of mRNA resulting in a dimmer florescent area. No hybridization of mRNA to DNA indicates those genes were inactive in that particular cell.
1. Expression level of thousands of genes can be studies simultaneously. For example this can be used in studying the effect of drug on gene expression. Genes whose expression is changed by viral infection can be studied by comparing gene expression between infected and healthy cells.
2. DNA microarray can be used to compare genome content between related organisms.
3. DNA microarray can be used to study the protein binding site occupancy throughout the genome.
4. Microarray can be used to check the contamination of food or cell culture by pathogens.
5. DNA microarray technology is used to identify single nucleotide polymorphism within/between the population.
6. DNA microarray is also used in detecting the exons of a genome.
7. DNA microarray is also used in forensic analysis, genotyping.
8. DNA microarray is used in evaluating gene mutations in cancer cells.
9. DNA microarray is used in identifying drug candidates.
10. DNA microarray is used in genetic linkage analysis.
Protein microarray is arrangement of purified proteins at high spatial density on glass slides. Most commonly used protein microarray is antibody microarray. These protein microarrays can be used to determine the protein-protein interactions, targets of biologically active small molecules.
Technology involved in protein microarray is similar to that of DNA microarray. Here instead of DNA externally synthesized, purified proteins are attached to the solid surface like glass slide or nano wells.
1. Protein microarray is used in identifying the protein-protein interactions.
2. Protein microarray is used to identify the tran script ion factors.
3. Protein microarray can also be used to identify the substrate for a particular enzyme. For example substrate for kinases can be identified.
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