Cell Membrane Transport Types: Types: Passive – does not require the use of energy (ATP) and usually moves molecules from high to low concentration. Active – requires the use of ATP and usually moves molecules or particles from an area of low concentration to high concentration.

Diffusion Defined: The movement of molecules from an area of higher concentration to an area of lower concentration. There must be a concentration gradient in place for this to occur. This movement continues to happen until equilibrium is met.

Osmosis Diffusion of water. Diffusion of water. Occurs only in the presence of a concentration gradient of water across a membrane. Occurs only in the presence of a concentration gradient of water across a membrane. Under most conditions a cell is isotonic to its body fluids. Under most conditions a cell is isotonic to its body fluids. If a cell is put into a hypotonic solution it will swell and lyse. If a cell is put into a hypotonic solution it will swell and lyse. If a cell is put into a hypertonic solution it will shrink and crenate. If a cell is put into a hypertonic solution it will shrink and crenate. These changes are a result of Osmotic pressure. These changes are a result of Osmotic pressure.

Filtration A diffusion process assisted by blood pressure. A solution is pushed through a filtration barrier. A diffusion process assisted by blood pressure. A solution is pushed through a filtration barrier. Large particles are kept behind and small particles and water are filtered out. Large particles are kept behind and small particles and water are filtered out. Occurs in the kidney’s to remove nitrogenous waste (urea) from the blood. Occurs in the kidney’s to remove nitrogenous waste (urea) from the blood.

Facilitated Transport Diffusion using an integral protein. Movement with the concentration gradient. Diffusion using an integral protein. Movement with the concentration gradient.

Active Transport Molecule moves against the concentration gradient; from low to high concentration. Molecule moves against the concentration gradient; from low to high concentration. ATP is used to change the shape of the integral protein to allow it to work as a pump. ATP is used to change the shape of the integral protein to allow it to work as a pump. Example: Sodium – Potassium Pump. Example: Sodium – Potassium Pump.

Endocytosis Also called phagocytosis and pinocytosis. Also called phagocytosis and pinocytosis. A process where a portion of the cell membrane invaginates to envelop a particle and then the membrane pinches off enclosing the particle in a vesicle. A process where a portion of the cell membrane invaginates to envelop a particle and then the membrane pinches off enclosing the particle in a vesicle.

Exocytosis A process where a vesicle fuses with the plasma membrane as secretion occurs. This allows wastes to leave the cell. A process where a vesicle fuses with the plasma membrane as secretion occurs. This allows wastes to leave the cell.