All cells take in nutrients and expel waste through the cell membrane. The cell membrane is selectively permeable, allowing some substances to pass through passively via diffusion, osmosis, or facilitated diffusion without using energy. Other substances require active transport using transport proteins and cellular energy to move against the concentration gradient into or out of the cell. There are two main types of active transport: endocytosis which surrounds and takes material into the cell, and exocytosis which expels material out of the cell.

1. Moving Cellular Materials

2. 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.

3. 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 .

4. 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.

5. Three types of Passive Transport Passive Transport Diffusion Osmosis Facilitated Diffusion

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

7. 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.

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

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

10. 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.

11. 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.