EK
Cell Membrane
It is the cell membrane which decides what may enter the cell. The lipids block everything out and the protein decides what may enter
Diffusion
Diffusion is the passive movement of molecules from a higher concentration to a lower concentration over a selctively permeable membrane. No energy is needed for diffusion to happen.
Diffusion happens with glucose, oxygen and acids
Osmosis
Osmosis is the passive movement of water molecules from a higher concentration to a lower concentration over a selectively permeable membrane. No energy is needed for osmosis to happen.
Osmosis only happens with water molecules.
Cells in different water concentrations
Low water concentration
Equal water concentration
High water concentration
More water molecules leave the cell than enter because the water concentration outside is higher than inside.
The cell is now plasmolyzed.
The cell stays the same because the water concentration is the same inside and outside the cell. Equally many water molecules leave the cell as enter the cell.
More water molecules enter the cell than leave the cell because the water concentration outside the cell is higher than inside. The cell will not burst because the cell wall will hold it together.
The cell is now turgid.
Plant Cell
Animal Cell
Low water concentration
Equal water concentration
High water concentration
More water molecules leave than enter the cell because the water concentration outside is lower than inside the cell. The cell shrinks.
The cell stays the same because the water concentration inside and outside the cell is the same. Equally many water molecules leave as enter the cell.
More water molecules enter than leave the cell because the water concentration outside the cell is higher than inside. The cell bursts because it doesn't have a cell wall to hold it together.
Active Transport
Active transport is the movement of molecules from a lower concentration to a higher concentration over a selectively permeable membrane using energy (ATP).
