Introduction
A microarray is a laboratory tool that can detect the expression of thousands of genes at the same time. Microarrays, also known as DNA microarrays, are microscope slides with thousands of tiny dots in predetermined locations, each of which encodes a known DNA sequence or gene. The names "gene chips" and "DNA chips" are widely used to describe these slides. Each slide's DNA molecules act as probes for detecting gene expression, also known as the transcriptome or the collection of messenger RNA (mRNA) transcripts expressed by a group of genes.
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Procedure
In order to do a microarray analysis, mRNA molecules are typically extracted from both an experimental and a reference sample. For example, the reference sample may come from a healthy individual, whereas the experimental sample could come from someone suffering from cancer. The two mRNA samples are then converted to complementary DNA (cDNA) and each sample is labelled with a unique fluorescent probe. For example, the experimental cDNA sample may be labelled with a red fluorescent dye, whereas the reference cDNA might be labelled with a green fluorescent dye. The two samples are then mixed together and allowed to bind to the microarray surface. The cDNA molecules bind to the DNA probes on the slide during the hybridization process. After hybridization, the microarray is scanned to identify the expression of each gene displayed on the slide.
Interpretation
If the expression of a certain gene is higher in the experimental sample than in the reference sample, the matching area on the microarray turns red. When the expression in the experimental sample is lower than in the reference sample, the spot turns green. Finally, the point turns yellow if the two samples have equal expression. Gene expression profiles, which reflect changes in the expression of many genes at the same time in response to a certain disease or medication, can be created using microarray data.
Applications
The microarray can be utilized in varied field pertaining to medical diagnosis and treatment, biotechnological and other researches, crime and security, and other such similar purposes.
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