As you saw in the animation, mRNA from the tissue sample hybridizes (sticks
to) to the complementary DNA on the microarray. The more mRNA present
in the tissue sample, more mRNA will hybridize to the DNA spot. Because
the mRNA has a red fluorescent label, more mRNA means a brighter
red light when that spot is scanned with the laser.
Typically, a microarray has over 200,000 DNA spots. In this photo
of an actual microarray, the mRNA has been labeled with a green
fluorescent label. A brighter green light indicates more mRNA is
present.
Scientists use very sophisticated statistics software and powerful
computers to analyze large amounts of data. They can spend over
six months analyzing data from one experiment.
In this case, we will only analyze a small portion of the microarray
that has 25 DNA spots.
Compare the microarray gene expression patterns to the
experimental sample. Which chemical class best matches the pattern
from the experimental sample?
