Plasma Membrane Transport

1. Plasma Membrane Transport Cells

2. Fluid Mosaic Model

3. Phospholipid

4. Cholesterol -immobilizes phospholipids (makes membranes less fluid and stronger)

5. Membrane Protein Functions

7. Passive Transport • Requires no energy • Occurs due to natural concentration gradient • Molecules move from high concentration to low concentration (DOWN the gradient) 3 Types • Diffusion • Osmosis • Faciliated Diffusion

8. Diffusion

9. Diffusion • A.K.A. simple diffusion • Movement of small molecules across a selectively permeable membrane from an area of HIGH concentration to an area of LOW concentration w/o the use of energy (DOWN the concentration gradient) e.g. O2, CO2, urea, & alcohol

10. Osmosis The diffusion of WATER across a selectively permeable membrane OSMOTIC PRESSURE The pressure exerted on plasma membranes in solution • Isotonic solution • Hypertonic solution • Hypotonic solution

11. Water Potential • The physical property predicting the direction in which water will flow, controlled by the solute concentration

12. (ψ) = Greek letter psi Water potentials(ψ) are a way of measuring the free-energy of water. Water will flow spontaneously from a high potential to a low potential, like a ball rolling down a hill.

13. Physical pressure due to air & the container

15. Cells in Isotonic Solution

16. Isotonic Solutions • If the concentration of solute (salt) is = on both sides, there will be no net movement of water • "ISO" means the same

17. Cells in Hypertonic Solution

18. Hypertonic Solutions • More solute (salt) molecules outside the cell, which causes water to be sucked out of the cell. • In plant cells, the central vacuole loses water and the cells shrink, causing plasmolysis resulting in the plant wilting. • In animal cells, the cells also shrink. • In both cases, the cell may die. • This is why it is dangerous to drink sea water

19. Plasmolysis A phenomenon in plant cells in which the cytoplasm shrivels and the plasma membrane pulls away from the cell wall when the cell loses water to a hypertonic environment.

20. Cells in Hypotonic Solution

21. Hypotonic Solutions • There are less solute (salt) molecules outside the cell, since salt sucks, water will move into the cell. • The cell will gain water and grow larger. In plant cells, the central vacuoles will fill and the plant becomes stiff and rigid, the cell wall keeps the plant from bursting • In animal cells, the cell may be in danger of bursting, organelles called CONTRACTILE VACUOLES will pump water out of the cell to prevent this.

23. Osmotic Potential The tendency of water to move across a selectively permeable membrane into a solution Determined by measuring the pressure required to stop the osmotic movement of water into the solution.

25. Osmosis Review

26. Facilitated DiffusionProtein Channel or Pore

27. Facilitated DiffusionProtein Carrier

29. Active Transport • Requires cell energy (ATP) to move molecules AGAINST the concentration gradient; from an area of LOW concentration to an area of HIGH concentration • Sodium–Potassium pump (Exchange 3 sodium ions for 2 potassium ions) • Hydrogen ion, or proton pump (Pump hydrogen ion against the concentration gradient)

30. Phosphorylation The addition of a phosphate (PO4) group (From ATP) to a protein or a small molecule This changes the protein shape

31. Active Transport (Uniport)

32. Active Transport Na-K Pump

33. Na-K Pump Antiport

35. Glucose-Sodium Symport

37. Proton (Hydrogen Ion) Pump

38. Bulk Media Transport • Endocytosis – Vesicle is created from the invagination of the plasma membrane, which pinches off, bringing large molecules into the cell • Pinocytosis – Cell drinking (endocytosis) • Phagocytosis – Cell eating (endocytosis) • Receptor Mediated Endocytosis – Substrate binds to receptor found on the plasma membrane to be brought into the cell • Exocytosis – Vesicle binds to the plasma membrane releasing the contents outside of the cell

39. Endocytosis

40. Pinocytosis

41. Phagocytosis

42. Receptor Mediated Endocytosis

43. Exocytosis