Moving Cellular Materials

All cells take in food, oxygen, and other substances from the environment.

Waste material must also move out of a cell into the environment.

Food, oxygen, molecules, and waste must pass through the cell membrane.

All cells are surrounded by a cell membrane that separates the cell from the outside environment.

The cell membrane is selectively permeable which means some substances can pass through the membrane while others cannot.

Passive Transport

Passive transport is the movement of materials through a cell membrane without the input of energy.

Molecules move from a more crowded area to a less crowded area WITHOUT

the use of energy.

Three types of Passive Transport

Passive Transport

Diffusion OsmosisFacilitatedDiffusion

Diffusion

Diffusion is the random movement of molecules from an area of higher concentration (more molecules) to an area of lower concentration (fewer molecules).

Dynamic Equilibrium

Molecules will continue to move from one area into another until the number of molecules is equal in the two areas.

This is called dynamic equilibrium.Molecules continue to move but there is

no change in concentration.

Osmosis

Osmosis is the diffusion of water molecules through a selectively permeable membrane.

Facilitated Diffusion

Facilitated Diffusion is the passive transport of materials across the plasma membrane with the aid of transport proteins.

Active Transport

Active transport is the movement of materials through a cell membrane using cellular energy.

Active transport involves using transport proteins which carry molecules from outside the cell to the inside.

In active transport molecules move from a less crowded area to a more crowded area WITH the use of energy.

Two types of Active Transport

Endocytosis is a process in which a cell surrounds and takes in material from its environment.

Exocytosis is the expulsion or secretion of materials from a cell.