GFP is a protein
found in Aequorea victoria, a bioluminescent jellyfish. In order to visualize a particular protein you can attach GPF to your protein so that it will fluoresce. This is done by taking the DNA
that encodes GFP and cloning it next to the gene
that encodes your gene
. This DNA is then added into your organism so that the organism makes the new fusion protein in the same way that it normally makes proteins.