1. Learning Targets “I Can...” -Describe the structure of the cell membrane. -Describe the function of protein channels and protein pumps that span the cell membrane. -Define “diffusion.” -Predict the direction of movement of particles across a membrane by diffusion. -Define “osmosis.” -Predict the direction of movement of water through a membrane by osmosis.

2. The Cell Membrane

3. Characteristics of the Cell Membrane 1. Recall that ALL cells have cell membranes 2.The cell membrane is a double-layered sheet called a phospholipid bilayer

4. CharacteristicsCharacteristics of the Cell Membrane

5. “WATER LOVING” “WATER FEARING”

6. Characteristics of the Cell Membrane Water on the OUTSIDE of the cell Water on the INSIDE Of the cell Lipids in the MIDDLE of the cell membrane

7. Characteristics of the Cell Membrane 3. The cell membrane regulates what enters and leaves the cell and also protects and supports the cell

8. Characteristics of the Cell Membrane 4.Proteins and carbohydrates are also found in and on the cell membrane a. Proteins form channels and pumps that help to move materials across the membrane b. Carbohydrates attach to these proteins and act as chemical identification cards so that individual cells can recognize each other

9. CharacteristicsCharacteristics of the Cell Membrane 5.Because there are so many molecules that make up the cell membrane and because these molecules move around within the membrane, scientists describe the membrane as a “fluid mosaic.” a. Fluid = constantly moving b. Mosaic = involving bits and pieces of different colors or materials

10. Movement Across the Cell Membrane 1. Materials that move through the cell membrane are not random because the cell membrane is selectively permeable

11. Movement Across the Cell Membrane 2. This means that some materials move easily, on their own, while other materials need the help of proteins 3. Some materials cannot move through the membranes AT ALL

12. Movement Across the Cell Membrane

13. Types of Passive Transport 1. Passive transport allows the cell to maintain homeostasis in its liquid environment. 2.Passive transport is the movement of molecules from one side of the membrane to the other 3.Because diffusion depends on the random movement of molecules, no additional energy is required in passive transport

14. Types of Passive Transport 4. Diffusion a. Particles (molecules) move from areas of HIGH particle concentration to areas of LOW particle concentration *What is a “particle”? Oxygen, Carbon Dioxide, Sugars, Vinegar, Iodine, etc.

15. Types of Passive Transport b. Example: Cup of water with particles + = particles

16. Types of Passive Transport

18. 5. Facilitated Diffusion: passive transport that utilizes the help of carrier proteins embedded in the cell membrane a. Osmosis is a type of facilitated diffusion that makes use of carrier proteins called aquaporins b. During osmosis, water moves from areas of LOW particle concentration to areas of HIGH particle concentration

19. Types of Passive Transport c. Example: Cup of water with particles + = particles +++ +++ + +++ +++ + + +++ + + +++ + + +

22. Learning Targets “I Can…” -Describe active transport. -Describe the role of vesicles in the cell. -Distinguish between endocytosis and exocytosis.

23. Types of Active Transport 1.Active transport is the movement of materials AGAINST the concentration gradient. 2.Active transport requires energy.energy a. Molecular Transport: small molecules and ions are carried across the membrane by proteins that act as pumps

24. Types of Active Transport 1.Active transport is the movement of materials AGAINST the concentration gradient. 2.Active transport requires energy. b. Bulk Transport: the transport of large molecules or even solid clumps of materialsusing vesiclesvesicles Endocytosis Exocytosis

25. References http://www.stolaf.edu/people/giannini/biologi cal%20anamations.html http://www.youtube.com/watch?v=wO1yq6Y TJDI