The Plasma Membrane

1. The Plasma Membrane Maintaining Homeostasis

2. Cell Membrane - Multiple names - plasma membrane, phospholipidbilayer, lipid bilayer, biological membrane -Controls what comes into the cell and what goes out, it is said to be selectively permeable -cell membrane is fluid, pieces move around feely this is called the fluid-mosaic model - Contains proteins * Transport (Channel and Carrier) * Adhesion * Recognition (Antigens) * Receptor Sites - Contains cholesterol to keep fluid

3. Tile Mosaic

4. Biological Membranes and Maintenance of Homeostasis Components to the Plasma Membrane Phospholipids –Two layers, that float over one another Chanel Proteins –allow large molecule to move into and out of the cell Receptor Proteins – used to identify the cell type, and allows for cell to cell communication, through the use of hormones etc

7. Maintaining Homeostasis- Passive Transport Osmosis and Diffusion Passive Transport- the unassisted movement of materials across the cell membrane that does not require energy, only for small molecules Diffusion – the movement of materials down a concentration gradient from high concentrations to lower concentrations Osmosis- special type of diffusion, that only refers to water moving down a concentration gradient from high to low concentrations Large molecules are trapped inside the cell, but water can move freely into and out of the cell For a cell to be happy or to be in equilibrium, the cell needs the same concentration of water on the inside of the cell as the outside of the cell Solutions – homogeneous mixture of two or more substances Solvent – the stuff the does the dissolving ( Ex: Water) Solute- the stuff that is being dissolved ( Ex: Salt)

8. Osmosis Animation

9. Types of Solutions - Hypertonic More water inside the cell then outside the cell Water moves out of the cell  cause the cell to shrink ( crenate)

10. Types of Solutions - Hypotonic Hypo = Hippo More water outside the cell then inside Water moves into the cell causes it to swell

11. Types of Solutions - Isotonic Same amount water inside the cell as outside No net movement of water, water moves in and water moves out but they balance each other out

15. Maintaining Homeostasis- Passive Transport Facilitated Diffusion Facilitated Diffusion-the assisted movement of material across the cell membrane through the use of channel (membrane) proteins -requires no energy

16. Maintaining Homeostasis- Active Transport Active Transport – the assisted movement of larger molecules across the cell membrane, through channel proteins. Molecules move up the concentration gradient from low concentrations to higher concentrations, thus the process requires energy EX: Sodium-Potassium Pump is required for proper nerve functioning

17. Interactive –w/ Sodium potassium pump Just Passing Through How Osmosis works

18. Cell Transport - Endo/ Exocytosis Process used by cells to import or export large molecules into and out of the cell Phagocytosis ( Cell Eating)- large objects, used to get rid of pathogens and to absorb large molecules Pinocytosis ( Cell Drinking)- used so the cell can obtain solute and single molecules such as a protein