1. FLUID MOSAIC MODEL

2. FLUID MOSAIC MODEL Model describing structure of the cell membrane
Model says cell membrane is not solid, fluid.
Has the consistency of olive oil

3. FUNCTIONS OF PLASMA MEMBRANE

4. FUNCTIONS OF PLASMA MEMBRANE
Protective barrier - contains cytoplasm (contents of the cell)

5. FUNCTIONS OF PLASMA MEMBRANE
Transport
Regulates movement of substances in / out of cell (selectively permeable)

6. FUNCTIONS OF PLASMA MEMBRANE
Cell recognition
Allows cells to identify surrounding cells

7. FUNCTIONS OF PLASMA MEMBRANE
Cellular Attachment
Cell membranes have junctions – surfaces which interlock keeps cells together – and surfaces which attach them to the extra cellular matrix.

8. FUNCTIONS OF PLASMA MEMBRANE
Signal Transduction
converts a mechanical/chemical stimulus to a cell into a specific cellular response.

9. FUNCTIONS OF PLASMA MEMBRANE
Enzyme Activity
Cells rely on thousands of different enzymes to catalyze metabolic reactions, many of these occur at the cell membrane.

10. STRUCTURE OF PLASMA MEMBRANE

11. MEMBRANE COMPONENTS Phospholipids Cholesterol
Proteins (intergral & peripheral)
Carbohydrates (glucose)

12. PHOSPHOLIPIDS Make up 30-70% of the cell membrane
Phospholipids are like triglycerides with a phosphate
Come together to make a fluid membrane

13. PHOSPHOLIPID ORIENTATION
In water, phospholipids form a bilayer
A cell membrane is a bilayer

14. PHOSPHOLIPID ORIENTATION
Liposome is a small vesicle, with an aqueous compartment surrounded by a bilayer

15. PHOSPHOLIPID ORIENTATION
PHOSPHATE HEADS – are water loving and point toward water
FATTY ACID TAILS – are water fearing and orient themselves to each other

17. PHOSPHATE HEAD – HYDROPHYLIC
FATTY ACID TAILS – HYDROPHOBIC

18. CLOSER LOOK OF THE PLASMA MEMBRANE

19. PROTEINS

20. INTEGRAL PROTEINS
Proteins surrounded by phospholipids which go through the membrane
Functions: serve as ion channels, membrane pumps, or receptors

21. FLUID MOSAIC MODEL

22. INTEGRAL PROTEINS

23. PERIPHERAL PROTEINS Proteins which attach to the membrane
Predominately interact with integral proteins
Can attach by weak hydrogen bonds
1. interaction by an amphipathic α-helix parallel to the membrane plane (in-plane membrane helix) 2. interaction by a hydrophobic loop 3. interaction by a covalently bound membrane lipid (lipidation) 4. electrostatic or ionic interactions with membrane lipids (e.g.through a calcium ion)

24. PERIPHERAL PROTEINS

25. GLYCOPROTEINS GLYCOPROTEINS found on the surface of the membrane
Serve as recognition sites for chemicals
Involved in cell to cell interactions

26. GLYCOLIPIDS Between phospholipids
Face extracellular fluid and serve as “cell identifiers”

27. CHOLESTEROL
Involved in keeping membrane “fluid”

28. GLYCOLIPIDS

29. REVIEW

30. http://bio-animations. blogspot

32. References
Original presentation by M.Bregar (Dante C.S.S.)
Modified by D. Machacek