Final answer:
GFP does not need an additional cofactor for fluorescence; its chromophore is formed by the protein's own amino acids through self-modification and an autocatalytic reaction, making answer E) 2 and 3 correct.
Step-by-step explanation:
The Green Fluorescent Protein (GFP) does not require an additional cofactor to absorb and emit light because the light-absorbing/emitting chromophore is formed through self-modification and an autocatalytic reaction. In other words, the chromophore within GFP self-catalyzes its formation from the protein's own amino acids, which means answer E) 2 and 3 is correct. Most fluorescent proteins require external molecules or cofactors to become fluorescent, but GFP is unique in its capability to form a chromophore without external assistance.
The reason why GFP (Green Fluorescent Protein) does not require an additional cofactor to absorb and emit light is because of its unique structure and self-modification process. Unlike most fluorescent proteins, GFP is a perfectly fluorescing molecule, meaning it is capable of absorbing and emitting light without the need for any additional factors or catalysts. The light absorbing and emitting chromophore in GFP is formed by a self-modification process called an autocatalytic reaction.