Proteins in the cell surface membranes of human cells and mouse cells were marked using fluorescent dyes. The human cells were given a red dye, whereas the mouse cells were given a green dye. A human cell and a mouse cell were then fused together to produce a hybrid cell. Initially, the two dyes stayed apart. After 40 minutes, the two dyes were spread evenly throughout the hybrid cell surface membrane. What accounts for this observation?
- AAll protein molecules in the cell surface membrane are fixed to structures within the cell, but phospholipid molecules move freely between them.
- BGroups of protein and phospholipid molecules in the cell surface membrane are attached to each other and move together.
- COnly protein molecules in the outer layer of the cell surface membrane can move freely between phospholipid molecules.
- DProtein molecules in the outer layer of the cell surface membrane and those which span the bilayer can move freely between phospholipid molecules.