Proteins in the cell surface membranes of human cells and mouse cells were marked with red and green fluorescent dyes, respectively. After a human cell was fused with a mouse cell, the dyes were first found in separate areas, but later they became evenly spread throughout. What explains 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.