Understanding Plasma Membrane: Structure, Function & Permeability

1. 4.1 Plasma Membrane Structure and Function • Regulates the entrance and exit of molecules into and out of the cell • Phospholipid bilayer with embedded proteins • Hydrophilic polar heads • Hydrophobic nonpolar tails • Cholesterol (animal cells)

2. Fluid-mosaic Model of Plasma Membrane Structure

3. 4.1 Plasma Membrane Structure and Function • Types of Membrane Proteins • Channel Proteins • Carrier Proteins • Cell Recognition Proteins • Receptor Proteins • Enzymatic

4. A Proteins

5. 4.2 Permeability of the Plasma Membrane • Differentially (selectively) Permeable • Factors that determine how a substance may be transported across a plasma membrane: • Size • Polar or Nonpolar

6. How Molecules Cross the Plasma Membrane

7. Passage of Molecules into and out of the CellKnow for test

8. 4.2 Permeability of the Plasma Membrane • Diffusion and Osmosis • Diffusion is the movement of molecules from an area of higher to lower concentration

9. Process of Diffusion

10. 4.2 Permeability of the Plasma Membrane • Diffusion and Osmosis • Diffusion is the movement of molecules from an area of higher to lower concentration • Oxygen and Carbon Dioxide are two gases that can diffuse through the plasma membrane

11. Gas Exchange in Lungs

12. 4.2 Permeability of the Plasma Membrane • Osmosis • Osmosis is the diffusion of water across a differentially permeable membrane.

13. 4.2 Permeability of the Plasma Membrane • Osmosis • Osmosis is the diffusion of water across a differentially permeable membrane. • Osmotic pressure is the pressure that develops in a system due to osmosis.

14. Osmosis Demonstration

15. 4.2 Permeability of the Plasma Membrane • Osmosis • Isotonic: the solute concentration is equal inside and outside of a cell • Hypotonic: a solution has a lower solute concentration than the inside of a cell • Hypertonic: a solution has a higher solute concentration than the inside of a cell

16. Osmosis in Animal and Plant Cells

17. 4.2 Permeability of the Plasma Membrane • Transport by Carrier Proteins • Carrier proteins combine with a molecule or ion to be transported across the membrane. • Carrier proteins are required for: • Facilitated Transport • Active Transport

18. Facilitated Transport • Small molecules that are not lipid-soluble • Molecules combine with carrier proteins • Molecules follow the concentration gradient • Energy is not required

19. 4.2 Permeability of the Plasma Membrane • Active Transport • Small molecules • Molecules combine with carrier proteins • Molecules move against the concentration gradient • Energy is required

20. The Sodium-Potassium Pump

21. 4.2 Permeability of the Plasma Membrane • Vesicle Formation • Transport of large molecules • Requires energy • Keeps the macromolecule contained

22. 4.2 Permeability of the Plasma Membrane • Vesicle Formation • Exocytosis - Vesicles form as a way to transport molecules out of a cell

23. Exocytosis

24. Vesicle Formation • Vesicle Formation • Endocytosis - Vesicles form as a way to transport molecules into a cell • Phagocytosis: Large,particulate matter • Pinocytosis: Liquids and small particles dissolved in liquid • Receptor Mediated Endocytosis: A type of pinocytosis that involves a coated pit

25. Three Methods of Endocytosis