In an experiment, the proteins in the cell surface membrane of a living cell were tagged with a fluorescent dye. A small region of the membrane was then viewed with a microscope. A laser was subsequently used to permanently eliminate the fluorescence of the dye molecules in this field of view. Later, fluorescence was observed to reappear in this field of view. What does this experiment demonstrate?
- AProteins are found only on the outer surface of cell surface membranes.
- BProteins in the outer layer of a bilayer do not penetrate into the inner layer.
- CProteins move freely in the phospholipids of a bilayer.
- DThe cell surface membrane of the cell is a bilayer.