What is green fluroescent protein?
GFP is a protein originally found in jellyfish. Being fluorescent, it glows green when illuminated with blue or ultraviolet light. More importantly, the gene for this protein was also isolated & intensively studied. This gene can be spliced into the DNA of some other organism and attached to one of its genes as a so-called REPORTER gene. When such a gene (being studied, attached to the GFP gene) is activated the GFP gene is also activated to produce GFP. So you just shine a blue light on the organism to see exactly where the gene that’s being studied has been activated. In other words, it acts as a visible marker of specific gene activity — extremely valuable to research. This earned a 2008 Nobel Prize for the chemists who isolated and developed GFP.
