Not long ago, scientists used to study gene expression by comparing one gene at a time. They would measure how much mRNA was produced in the control treatment and how much mRNA was produced in the experimental treatment. A pretty slow process!

With new scientific advancements, scientists can now study many genes at one time. Several organisms, including zebrafish and humans, have been well studied and scientists know where all their genes are and what they do. So they have a better understanding of how organisms are affected by changes in their gene expression.

How do scientists study many genes at a time? One powerful analytical tool is the microarray (micro: small, array: arranged in a table). A microarray contains copies of many different genes (DNA) and can measure the type and amount of mRNA in an organism.

What exactly does a microarray tell us?

  1. Snapshot: Microarrays are a picture of what is happening within cells at one moment in time.

  2. Comparison: Microarrays allow a scientist to compare the experimental treatment to the control treatment.

  3. Identity: Microarrays can tell you what class of chemical is present based on the unique pattern created by the different genes expressed. They will not tell you the exact chemical but help you narrow down the suspects.

In the Lab