Why is a gene for a fluorescent protein used rather than one for an enzyme that produces fluorescent molecule? Green fluorescent protein (GFP) is a small protein that emits bright green fluorescence in blue light. It was first isolated from the jellyfish. The gene coding for GFP can be expressed in bacteria, and so it is often used as a marker to show successful uptake of a gene by the bacterium. What is the **advantage** of using the gene for GFP to produce easily detectable fluorescence, rather than using a gene for an enzyme that produces a fluorescent substance? Ps. The original question I got was to explain about the **disadvantage** , which is that GFP may not fluoresce very brightly and so may be difficult to detect. Thank you for your help.

GFP has a lot of advantages:

* The detection of the fluorescence works directly and doesn't need a lysis step or the uptake of a reagent.
* Fluorescence can be detected directly using a fluorescence or confokal microscope with the cells. This can be done while growing them on plates (works for bacteria and eukaryotic cell culture).
* You can sort labelled cells using a flow cytometer.
* direct tagging of proteins and their subsequent localisation on the cell is possible.
* GFP is rather stable in the cells and not toxic.