1. Warm Up – 11/11
Compare simple diffusion and facilitated diffusion. Similarities and differences! List two characteristics of molecules that can move across cell membranes through simple diffusion. When do molecules stop moving on the concentration gradient? Sketch the cell membrane – Include: phospholipid, transport proteins, lipid bilayer, head, and tail

2. Cell Membrane The cell membrane is Selectively Permeable
Made of double-layer of Phospholipids.
Named the phospholipid bilayer.
Strong and flexible barrier
The cell membrane is Selectively Permeable
Some substances can cross the membrane easily, while others cannot!

3. The Properties of Lipids
Phospholipid Review
Fatty acid portions of such a lipid are hydrophobic, or “water-hating”
The opposite end of the molecule is hydrophilic, or “water-loving.”

4. The Properties of Lipids
The hydrophobic fatty acid “tails” cluster together
The hydrophilic “heads” are attracted to water inside and outside of the cell.
A lipid bilayer is the result.

5. The Fluid Mosaic Model
There are also carbohydrates and proteins embedded in the membrane.
The membrane contains several different molecules, but remains flexible (Like a liquid)

6. Cellular Transport

7. Cell Membrane Structure
Phospholipid Bilayer
Proteins: Embedded in between the phospholipids
Fluid Mosaic Model
Phospholipid
Protein
Phospholipid Bilayer
Phospholipid
Polar Head
Fatty Acid Chains
Slide 3.7a
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

8. Plasma Membrane Functions
Maintains boundaries
Controls what enters and leaves the cell
Figure 3.2
Slide 3.7b
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

9. The cell membrane is selectively permeable
Some materials are able to….
Move in and out of the cell freely
Pass through at certain times
Others cannot pass through the membrane.

10. List two characteristics that can prevent molecules from passing through the cell membrane.

11. Size – Size limits a molecules ability to pass through the membrane
Charge – Charged molecules have a hard time passing in between the nonpolar tails.

12. Predict the results
What do you predict will happen if food coloring is dropped into a beaker of water?

13. There are Two Types of Cellular Transport
Passive Transport & Active Transport

14. There are three forms of passive transport.
a. Passive Transport
-Molecules move from a high concentration to a low concentration.
-No energy is required
There are three forms of passive transport.
A. Simple Diffusion
B. Facilitated Diffusion
C. Osmosis

15. Types of Passive Transport
A. Simple Diffusion
Types of Passive Transport
Molecules move across the cell membrane through the phospholipids
Direction of flow: high concentration to low concentration
No energy is required
Examples: Carbon Dioxide & Oxygen

16. B. Facilitated Diffusion
The diffusion of larger or charged molecules through a protein molecule
Molecules move from a high concentration to low concentration
No energy is required
Glucose is an example of a molecule that moves by facilitated diffusion

17. C. Osmosis No energy is required
Osmosis is the facilitated diffusion of water molecules across a selectively permeable membrane.
Direction of Movement is from a high concentration to low concentration
No energy is required
The diffusion of water molecules is OSMOSIS.

18. Aquaporin!!
Water molecules

19. Osmosis
What effect would osmosis have on a cell if water rushed into it?
What if water rushed out of it?

20. Osmosis Three possible effects of osmosis on cells
Isotonic: amount of solutes is equal inside and outside of the cell.
Hypertonic: higher amount of solutes outside of the cell.
Hypotonic: lower amount of solutes

21. Osmosis Hypertonic Hypotonic Isotonic
Always refers to the concentration of solutes outside of the cell!!!

22. DIFFUSION OCCURS THROUGH THE CELL MEMBRANE OF CELLS!!!!!
The movement of molecules from a high concentration to a low concentration
DOES DIFFUSION REQUIRE ENERGY?
Diffusion does NOT require energy
DIFFUSION OCCURS THROUGH THE CELL MEMBRANE OF CELLS!!!!!

23. HOW IS DIFFUSION IMPORTANT FOR YOUR SURVIVAL?
Cellular Transport!!!
Materials move across cell membranes (into or out of cells)
Materials can be used by the cell or transported by the cell throughout the organism.
What types of materials do cells transport through out your body?
Water, Oxygen, Carbon Dioxide, Glucose, etc

24. ACTIVE TRANSPORT

25. Types of Active Transport include: Protein Pumps Endocytosis
Movement of molecules into or out of cells from low concentration to high concentration
Requires energy to occur (ATP).
Types of Active Transport include:
Protein Pumps
Endocytosis
Exocytosis

26. The bonds between the ATP parts are broken A-P-P P
Active Transport
Requires Energy (ATP)
ATP (adenosine triphosphate) is a molecule that contains energy in its bonds
A-P-P~P
The bonds between the ATP parts are broken
A-P-P P
Energy within the bond is released and used by our cells for active transport
A-P-P P (energy released)

27. Protein Pumps: a specialized protein pumps a substance across the membrane
Movement is from low concentration to high concentration
Requires energy (ATP)
The sodium/potassium pump is an example (needed to send impulses along nerve cells)
Sodium-Potassium Pump - Video

28. Endocytosis Taking materials into the cell with a vesicle.
Movement is from low to high concentration
Energy is required to surround materials with in a vesicle
Examples of Endocytosis:
Phagocytosis brings solids into the cell (WBC engulfing disease causing bacteria)
Pinocytosis brings liquids into the cell

29. Endocytosis

30. Exocytosis Exporting large materials out of a cell using a vesicle.
The movement is from low to high concentration
Cells use energy to transport material in vesicles.
Example:
A cell releasing indigestible material

31. Exocytosis