Studies of the endomembrane system often involve the use of a protein that can emit a green fluorescence (glow). a researcher wants to make a video of cell behavior, so she initially tags the outer nuclear envelope of a cell with the fluorescent tag and records for several hours. later, she sees that the tag is part of a secretory vesicle. the ability to stain protein molecules with a fluorescent dye would most clearly allow researchers to go beyond what they could previously detect with a microscope by allowing them to