1. PASSIVE AND ACTIVE TRANSPORT IN CELLS

2. Passive Transport
Movement across the cell membrane that does not require the cell’s energy

3. Concentration Gradient
A difference in concentration of a substance throughout a space

4. Equilibrium
Concentration of a substance is equal throughout a space

5. Diffusion
Movement of a substance from an area of high concentration to an area of low concentration

6. Selectively Permeable Membrane
Only allows some substances to pass through

7. Diffusion Through Ion Channels
A transport protein with a polar pore that allows ions to diffuse into and out of the cell
The electrical charge of an ion can affect its ability to diffuse- The inside of a typical cell is negative, so it is more likely a positive ion will diffuse into the cell and a negative ion will diffuse out.
Opposites attract and like charges repel

8. Carrier Proteins
Most cells have a different kind of protein that can bind to a specific substance on one side of the cell membrane and carry it to the other side

9. Facilitated Diffusion
Carrier proteins are used to transport specific substances without using the cell’s energy

10. OSMOSIS Diffusion of water across a selectively permeable membrane
Hypertonic- water diffuses out of cell- cell shrinks
Hypotonic- water diffuses into cell- cell swells
Isotonic- water diffuses into and out of cells at equal rates

12. Active Transport
Movement of a substance across the cell membrane against the concentration gradient – against diffusion i.e. from low to high concentration
REQUIRES ENERGY from the cell supplied by ATP

13. VESICLES
Substances that are too large to be transported by carrier proteins, such as proteins and polysaccharides, are moved across the membrane by vesicles
Endocytosis- movement of a substance into a cell by a vesicle
Exocytosis- movement of a substance out of a cell by a vesicle

14. Endocytosis

15. Exocytosis

16. Endocytosis and Exocytosis

17. Receptor Proteins
Cells must also respond to important information and filter out unimportant information. To receive messages sent by signal molecules, cell
membranes contain
specialized proteins called
receptor proteins that
bind to the signal molecules
allowing the cell to respond
to the signal