A scientist was studying the production of a protein that was released by an animal cell into a culture medium, she found that the protein only appeared in the culture medium after the added a few drops of a hormone to the cell. Before adding the hormone, she labelled the protein inside the cell with a fluorescent dye and looked at the cell under the lgiht microscope. The dye was seen in flattened sheets and tube. like structures throughout the cell, and in stacks of flattened sac-like structures. after adding the hormone, the dye was aslo seen as small dots clustered against the cell membrane, Which statement most likely explains these observations?