Bacteria can be genetically engineered to produce useful proteins such as Green Fluorescent Protein (GFP).

In an experiment, scientists modified a population of bacteria using plasmids containing a marker gene and the gene for GFP. They observed the following:

• 1 in 250 bacteria successfully took up a plasmid.
• 1 in 800 of the plasmids taken up by the bacteria contained the GFP gene.