1. Cell Membrane Structure and Function

2. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. QOD – What makes the cell membrane selectively permeable? LG - Understand how cells maintain homeostasis by explaining how different environmental conditions can affect the cell. 2

3. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Phosopholipid Bi-Layer 3 -polar heads are hydrophilic “water loving” -tails (fatty acids) are hydrophobic “water fearing” and face inward

4. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4 Predict the two reasons things can’t directly go through the membrane: Selectively Permeable 1)Size (duh) 2)Polarity (from last unit)

5. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 5 The cell membrane only lets certain substances in and out of the cell Selectively Permeable

6. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Membrane Design 6 fluid-mosaic model a. Fluid = pliable/easily moved b. Mosaic = made of many different molecules (lipids, proteins, carbohydrates) Cell Membrane Animation

7. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Cholesterol Type of steroid (lipid) Changes fluidity of cell membrane Higher temps – stiffens membrane Lower temps – prevents membrane from freezing

8. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Proteins 8 Recognition Proteins Proteins that have carbohydrate chains attached Carbohydrate chains aid in cell identification “Name Tags” Example: Red Blood Cells (A, B), Identify Viruses as foreign Receptor Proteins Proteins that receive chemical signals from other cells Such as nervous system cells

9. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Channel Proteins Proteins that involved in letting certain substances in and out of cells Aquaporins- let water in and out of cells Proteins

10. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10 Integral Proteins that cross both layers of the phosphoplipid bilayer Peripheral proteins that are only on the top half or bottom half of the phospholipid bilayer Proteins