How does the cell membrane change shape?
The cell membrane is rather fluid but also slightly rigid. This allows the cell to change shape but it cannot change shape very much.
Most of the membrane is composed of phospholipid molecules. These allow the membrane to be rather fluid.
Embedded in this membrane are proteins which give some structure to the membrane. The 3rd component are proteins or glycolipids.
The membrane can seal itself if pierced by something very thin like a pin. But it will burst if it takes in too much water.
The proteins sort of float on the surface of the membrane like islands in the sea.
Cholesterol is also found in the membrane. It prevents lower temperatures from inhibiting the fluidity of the membrane and prevents higher temperatures from increasing fluidity.
Cholesterol is only found in animal cells.
The carbohydrates that are in plasma membranes are bound either to proteins or to the lipids. They form sites on the surface that allow the cells to recognize each other.
This is important because it all dolls the immune system to determine whether a cell is foreign (non-self) or are body cells (self).