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DNA microarray technology is used in genetic and medical research to allow scientists to study the activity of several thousand genes at the same time, as well as the relationship between them. In the past, scientists were only able to analyze a few genes at once. With the introduction of DNA microarrary technology, the activity of thousands of genes can be monitored simultaneously. Some of the health conditions that scientists use this technology to research gene activity include heart disease, cancer, and obesity. It also enables scientists to classify cancers based on where they originate, and the pattern of gene activity in the tumor cell.
A DNA microarray is made up of a stamp-sized slide that contains molecules known as DNA, the genetic code for an organism or one of its parts. The DNA is placed onto the slide in a specific sequence and in a pattern of regularly spaced horizontal and vertical lines by a robotic machine. The specific sequence and spacing of the DNA allows scientists to know the sequence of the gene(s) being used.
Before a scientist is able to measure the activity of a gene on the slide, a tissue sample from a patient, usually blood, needs to be collected. The tissue sample is placed in a solution and allows for the collection of mRNA, a product from an expressed gene that transports information from a nucleus to other parts of a cell to make proteins. The mRNA is complimentary to the strand of DNA it was copied from.
Once the mRNA is collected, a scientist will bind a fluorescent dye to the mRNA and it will be placed onto the slide by a robotic machine. The mRNA that is complimentary to the DNA will bind with its complement. Since the sequence of the DNA that was placed on the slide is known, the mRNA that binds with the DNA indicates the specific DNA sequence that is expressed in the cell.
To view the genes, a scanner will measure the fluorescent areas of the DNA microarray. The brightness of the fluorescent dye shows the activity of a gene and the absence of fluorescent dye indicates that a gene is not active. Therefore, the brighter the fluorescent dye, the more active the gene is. The lighter the fluorescent dye, the less active the gene is.
Knowing the activity of a gene can help be determine if a gene that is overexpressed can cause a specific disease. In a clinical setting, if the overexpression of a gene has already been determined to cause a specific disease, a tissue sample can be taken from a patient and a scientist can use the DNA microarray technology to measure the expression of the targeted gene to help determine if a specific gene could be the cause of the disease that the patient has. DNA microarray is a powerful way to determine which genes are involved in causing a specific disease.
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