Question

Know generally how monitor changes in the expression of large numbers of genes:

Answer 1

Answer:

Microarray technology is used to monitor changes in the expression of a large number of genes.

Earlier technologies such as reporter gene constructs or GFP fusions, Quantitative RT PCR and Northern analyses were used to study and monitor the expression of only a single gene at a time. However, with the advent of technology, DNA microarrays are being extensively used to study the gene expression of thousands of genes at once.

In a DNA microarray method, DNA molecules that are printed at high density are used to determine the level of RNA or DNA in a given sample. The usual technique involves mRNA isolation as the first step. After this, a cDNA copy is produced by reverse transcriptase enzyme using fluorescently labeled nucleotides. The cDNA mixture is then applied to a microarray which contains copies of ssDNA fragments from the genes (fixed on microscope slides). Each spot contains a different gene. The cDNA then hybridizes with the complementary DNA. The excess cDNA is then rinsed off and microarray is scanned for the detection of fluorescence signal.