Question

You are interpreting data on a DNA chip or microarray. You expose the chip to a mixture of two cDNA populations: one from cells that were not treated with a glucocorticoid hormone (untreated controls; labeled with a red fluorescent dye) and a population from cells that were treated with glucocorticoid hormones (glucocorticoid-treated; labeled with green fluorescent dye). You look at a spot on the chip representing the gene for glutamyltransferase, a gene that is turned on by glucocorticoid treatment, but is not expressed in its absence. What color should the spot representing the glutamyltransferase gene be?

1) red
2) green
3) yellow
4) black

Answer 1

The spot representing the glutamyltransferase gene on a DNA microarray will appear green due to hybridization with cDNA from glucocorticoid-treated cells, which express this gene and are labeled with a green dye.

Step-by-step explanation:

When interpreting data on a DNA microarray, the result of the spot representing the glutamyltransferase gene should appear green. This is due to the labeling of the cDNA from cells treated with glucocorticoid hormones with a green fluorescent dye.

Since glutamyltransferase is a gene that is turned on by glucocorticoid treatment, only the treated cells expressing this gene will hybridize at this spot, and therefore, the spot will fluoresce green when viewed under a microscope.