1. Passive and Active Transport
Chapter 8

2. Cell Membrane
Phospholipid bilayer – two layers of phospholipids back to back
Phosphate Heads – polar – water soluble - hydrophilic
Lipid Tails – non-polar – water insoluble – hydrophobic

3. Cell Membrane

4. Cell Membrane

5. Cell Membrane
Cholesterol stabilizes the membrane by preventing the lipid tails from sticking together
Proteins help regulate what enters and exits the cell
Carbs stick out from the membrane to identify chemical signals

6. What is Cell Transport?
Discovering how molecules travel across the cell membrane.
Maintains homeostasis for the cell
There are 2 types of transport

7. Passive Transport
Passive Transport – moving particles across the cell membrane from high to low concentration using no energy
There are 3 examples

8. Passive Transport
Facilitated Diffusion – uses channel or carrier proteins to move molecules from a high to low concentration
Channel proteins allow easier travel for larger molecules
Carrier proteins change shape to help molecules to travel through
Diffusion – moving any type of molecule across the cell membrane from a high to low concentration

9. Facilitated Diffusion

10. Diffusion

11. Osmosis Osmosis – diffusion of water across a cell membrane
Water travels from a high to low concentration
Concentration Gradient – unequal distribution of particles that controls osmosis
3 different solutions

12. But First… Solute – a substance that is dissolved in another substance
Ex. Salt, Sugar
Solvent – a substance that dissolves other substances
Ex. Water

13. Osmosis
Isotonic Solution – the concentration of the solute inside the cell is the same as the concentration of the solute outside of the cell
Water moves in and out of the cell at the same rate

14. Isotonic Solution

15. Osmosis
Hypotonic Solution – The concentration of solute outside the cell is smaller than inside the cell
There is more water outside the cell than inside
Water moves into the cell
The Cell Swells

16. Hypotonic Solution

17. Hypertonic Solution
Hypertonic Solution – The concentration of solute outside the cell is greater than inside the cell
There is more water inside the cell than outside
Water moves out of the cell
The Cell Shrinks

18. Hypertonic Solution

19. Active Transport
Active Transport – moving particles across the cell membrane from low to high concentration using energy
Uses carrier proteins
Uses 2 Processes

20. Active Transport
Endocytosis – the cell membrane encloses and forms around large particles in order to let it pass through
Exocytosis – the expulsion of materials, waste, and hormones from the cell

21. Transport Protein
Protein embedded in the cell membrane responsible for picking up or passing molecules through the cell membrane. This requires energy.

22. Endocytosis

23. Exocytosis

24. Why Is Active Transport Important?
Rid the cell of toxins
Movement to avoid danger or to find food, water, and or mates
Synthesizing needed molecules