1. Cell Membrane and what it does for the cell.

2. Phospholipid Bilayer

3. Synonyms
Plasma Membrane
Cell Membrane
Phospholipid Bilayer

4. Membrane up close Hydrophobic Hydrophilic Hydro Phobic Repels water
Loves water

5. Phospholipid Up Close

6. Insane in the Membrane – things on the membrane
Carbohydrate Chain – acts like an identification tag for the cell
Protein Channels – used to transport molecules in and out of the cell
Proteins – transmit and receive signals to other cells

8. Types of Transport Across Cell Membranes

9. Transport through membranes
2 ways
Passive transport: movement of substances across a membrane
Does not use energy
Examples: Diffusion, Osmosis, Facilitated Diffusion
Active transport: movement of molecules (or larger particles) through the cell membrane
Uses energy
Examples: Na+/K+ Pump, Endocytosis, Exocytosis

10. Diffusion Molecules move from area of HIGH to LOW concentration
NO energy required
What is the goal of diffusion?

11. Diffusion of Liquids

12. Facilitated Diffusion
Movement of specific molecules through proteins channels
Why called facilitated?
Types of Proteins that move molecules
Carrier and Channel

13. Types of Proteins A) Channel Protein – doesn’t change shape
B) Carrier Protein – changes shape

14. Diffusion across a membrane Semipermeable membrane
Osmosis
Water moves from HIGH concentration (low solute) to LOW concentration (high solute) concentration
Diffusion of water across a semi-membrane
Diffusion across a membrane
Semipermeable membrane

15. Diffusion of H2O Across A Membrane
High H2O potential Low solute concentration
Low H2O potential High solute concentration

16. Ultimate Goal of Diffusion and Osmosis
Reach a state of DYNAMIC EQUILIBRIUM – and ultimately have HOMEOSTASIS.
Dynamic Equilibrium – continuous movement of molecules across the membrane, but there is no change in concentration.
Homeostasis – body’s attempt to maintain stable internal conditions.

17. Types of Solutions
Hypotonic
Hypo
Hypertonic
Hyper
Isotonic
Iso

18. What happens when you put cells in different types of Solutions?
Cell on left is a typical sample of red blood cells.
Cells on the right have been put in a hypotonic solution. If left there long enough, the cells will burst open. Water from the solution is moving into the cells.

19. What happens when you put cells in different types of Solutions?
Cell on left is a typical sample of red blood cells.
Cells on the right have been put in a hypertonic solution. The cells have lost water and are starting to shrivel.

20. Cell in Hypotonic Solution
10% NaCL 90% H2O
CELL
20% NaCL
80% H2O
What is the direction of water movement?

21. Cells in a Hypertonic Solution
15% NaCL 85% H2O
ENVIRONMENT
CELL
5% NaCL
95% H2O
What is the direction of water movement?

22. Cell in Isotonic Solution
10% NaCL 90% H2O
ENVIRONMENT
CELL
NO NET MOVEMENT
10% NaCL
90% H2O
What is the direction of water movement?
equilibrium
The cell is at _______________.

23. Active Transport – movement across the membrane with Energy
ATP is the cell’s energy
What organelle do you think would make ATP in your cells?
ATP is used in Active Transport

24. Why do some types of transport need energy?
Active Transport moves molecules from LOW concentrations of solutes to HIGH concentrations of solutes.
We call this moving AGAINST the CONCENTRATION GRADIENT.
In Diffusion and Osmosis – molecules move WITH the CONCENTRATION GRADIENT.

25. Na+/K+ ATPase Pump
3 Na+ move out and ATP binds to protein – causes the protein to open up to the outside of the cell.
This allows 2 K+ to enter the cell. ADP can bind to its other Phosphate to become ATP.
Purpose of this pump – maintain Na+ and K+ levels inside and outside of the cell.

26. Na+/K+ ATPase Pump Another use
Glucose sometimes has to enter the cell even when the concentration of glucose inside the cell is really HIGH, so ENERGY is needed.
When the 3 Na+ get pushed outside of the cell in the pump, they can reenter the cell if they tag along with a Glucose molecule and enter through a channel protein – this is called COUPLING – when 2 different molecules use the same protein channel at the same time.

27. Endocytosis - Active

28. Exocytosis - Active

29. Links for Concepts in Motion