1. Pre-class activity 11/3 A cell membrane is responsible for maintaining the environment of a cell by determining which substances to let in and out of the cell. Which of the 7 properties of life (from chapter one) best matches the function of the cell membrane? Metabolism ResponsivenessReproduction Growth HomeostasisHeredity Cell Organization The maintenance of a constant internal state in a changing environment Homework (due 11/5) Vocab, 1 st 8 terms

2. Organization of the Cell Membrane Phospholipid Bilayer (Water loving)(Water hating)

3. Membrane Proteins Proteins have both polar and nonpolar parts. The nonpolar parts are attracted to the inside of the membrane while the polar parts are attracted to the outside of the membrane. This is how proteins can become embedded in the cell membrane.

4. 4 Types of Proteins Cell Surface Markers A chain of sugars attached to proteins on the cell’s surface Receptor Proteins Cells sense their surroundings by binding to certain substances outside the cell which cause changes inside the cell. Enzymes Help with biochemical reactions Transport Proteins Aid the movement of substances into and out of the cell that wouldn’t normally be able to pass through the bilayer

5. Pre-class Activity 11/5 How does that cell membrane function to maintain homeostasis (balance) in the cell? It allows the movements of substances in and out of the cell. As nutrients are used up or wastes build up, they can be replenished or removed to create balance in the cell.

6. Cell Transport (How cell move substances across the cell membrane) Passive Transport (Does not require energy) Active Transport (Requires Energy) DiffusionOsmosis SimpleFacilitated PumpsVesicles EndocytosisExocytosis

7. Solutions A mixture of a solid and a liquid Solvent Solute Dilute Concentrated Concentration/Strength

8. Diffusion The movement of substances from an area of high concentration to an area of low concentration (concentration gradient) to create balance.

9. Simple Diffusion vs. Facilitated Diffusion Simple Diffusion Small, non-polar molecules pass directly through the bilayer Facilitated Diffusion Large, polar molecules and ions required channel proteins or carrier proteins to cross the membrane.

10. Pre-class Activity 11/11/08 Examine these two glasses of KoolAid. Which has the greater amount of solute? How can you tell? Homework Last 3 vocab Terms, Chapter 8 Vocab Quiz Friday 11/14 AB B Darker in color, less dilute

11. Pre-class Activity 11/12/08 Why do these two plants look different? What structure within the plant cell has been most effected by this change? Vacuole

12. Osmosis The movement of water across a selectively permeable membrane from an area of high concentration of water to an area of low concentration of water.

13. Movement of Water When the extracellular fluid is……. Hypertonic High Solute Low Water Hypotonic Low Solute High Water Isotonic Equal Solute Equal Water With respect to the inside of the cell

14. Cell Transport (How cell move substances across the cell membrane) Passive Transport (Does not require energy) Active Transport (Requires Energy) DiffusionOsmosis SimpleFacilitated PumpsVesicles EndocytosisExocytosis

15. Passive Transport vs. Active Transport + With the Concentration GradientAgainst the Concentration Gradient No Energy RequiredEnergy Required

16. Active Transport - Pumps Sodium-Potassium Pump

17. Active Transport - Vesicles

18. Pre-Class Activity 11/17/08 +++++++ ++++++++++++++ If the substance was able to move through the membrane which direction would it go? What is the name of the process that describes the motion of particles? Diffusion If only water was able to move through the membrane which direction would it go? What is the name of the process that describes the motion of water? Osmosis Homework (due 11/18): Chapter 8 Section Quizes Chapter 8 Test: Thursday

19. Cell Communication Sending Signals How signals are sent depends on how far away target cells are. Close targets are signaled by direct contact Far away targets are signaled by chemicals and nerve cells Signals can come from within or outside of the body

20. Cell Communication Receiving Signals Receptor Proteins receive specific signals by binding substances at specific binding sites. Receptor proteins enable a cell to detect its environment Once it binds a signal molecule, the protein changes its shape in the membrane which relays information into the cytoplasm

21. Cell Communication Responding to Signals Once a signal molecule binds to a receptor protein, one of three things can occur 1.Change in the permeability of the membrane 2.Activation of enzymes that trigger chemical reactions in the cell 3.Formation of a second messenger (acts as a signal molecule inside the cell)