1. The Cell Membrane

2. What is the cell membrane mainly composed of?
What is the function of the cell membrane?

3. Cell membrane regulates what enters and leaves the cell.
The cell membrane allows nutrients and compounds needed for cellular functions into the cell, and wastes from cellular functions out of the cell.
How does the cell do this??

4. The Phospholipid Bilayer
The cell membrane is two layers of phospholipids (bi meaning two)
They are arranged such that the fatty acid tails are facing inward and the phosphate heads are facing out (either into the cell or into the intermembrane space)

6. Passive and Active Transport
Cell Transport
Passive and Active Transport

7. Passive Transport
The movement of materials across a membrane without the use of energy
Three main types of passive transport:
Diffusion
Osmosis
Facilitated Diffusion

8. Diffusion
Molecules move from an area of high concentration to an area of low concentration.
Most molecules move from a of high concentration to a low concentration

9. Osmosis Diffusion of water across a selectively permeable membrane.
NOTE – osmosis is diffusion, so the water will move from an area of high water concentration to an area of low water concentration.
-- water will move until an equilibrium is reached.

11. Facilitated Diffusion
Protein carrier molecules in the cell membrane allow molecules and ions to passively flow from an area of high concentration to low concentration across the cell membrane.

12. Active Transport
The use of cellular energy to move materials across a cell membrane against the concentration gradient (from an area of low concentration to an area of high concentration)
Active transport can be completed by:
Transport carrier proteins
Endocytosis
Exocytosis

13. Endocytosis Process by which cells bring in materials. Two main types:
Pinocytosis (liquids)
Phagocytosis (solid)

14. Exocytosis Large molecules are released from the cell.
E.g. hormones, neurotransmitters, and waste materials.