1. Structure of the Cell Membrane
The two layers are made of lipids and proteins are embedded in them
Double layer = bilayer

2. Membrane Proteins
Peripheral proteins – proteins attached to the surface of the cell membrane
Integral proteins – proteins that go through the membrane – carbohydrates can be attached to them
Transport molecules through the lipid bilayer (channels and pumps)

3. Fluid Mosaic Model Lipid molecules that form the membrane are fluid
The proteins are free to move about
The cell membrane has fluid properties

4. Carbohydrates Attach to the proteins or lipids
Function as Id cards – allows cells to interact with one another

7. The Cell Membrane

8. Cell Membrane plasma membrane
Separates the cell from the surrounding environment
Controls the movement of materials in and out of the cell – lets some in and some out
Protection
Support

9. Structure of the Cell Membrane
The two layers are made of lipids and proteins are embedded in them
Double layer = bilayer

10. Membrane Proteins
Peripheral proteins – proteins attached to the surface of the cell membrane
Integral proteins – proteins that go through the membrane – carbohydrates can be attached to them
Transport molecules through the lipid bilayer (channels and pumps)

11. Fluid Mosaic Model Lipid molecules that form the membrane are fluid
The proteins are free to move about
The cell membrane has fluid properties

13. 5-4 Movement of Materials through the cell membrane

14. Every cell is in a liquid environment
Liquid environment makes it easier for food, oxygen and water to move in and out

15. Diffusion – Passive Transport (No energy, No ATP)
Molecules are in constant motion
Tend to spread out randomly in space
Molecules move from an area of greater concentration to an area of lesser concentration
Diffusion – process by which molecules move from greater to lesser concentration

18. Equilibrium
Concentration of substances on both sides of the membrane are the same
Molecules are still moving back and forth but equally
Molecules always try to get to this

20. Permeability Determines what moves across
Permeable – substance can move in and out
Impermeable – substance can’t move
Selectively permeable – some things can pass some can’t – characteristic of biological membranes

21. Osmosis – Passive Transport
Diffusion of water molecules across a selectively permeable membrane
Water passes through cell membranes rapidly
Moves greater to lesser

23. Hypotonic solution – Solution in which the concentration of solutes is lower than inside the cell

24. Isotonic solution – Solution in which the concentration of solutes in and outside the cell is equal

25. Hypertonic solution – solution in which the concentration of solutes is higher than inside the cell

27. Osmosis
Hypertonic
Hypotonic
Isotonic
Normal
plasmolyzed
wilted

28. Osmotic pressure Turgor pressure
force exerted by water molecules hitting the membrane
Causes water to move
High pressure to low pressure

29. Osmotic pressure – Problems for a cell
Cytoplasm filled with salts, sugars and proteins
Cell has a low concentration of water inside as compared to outside
Water would continuously move in – cell would burst

30. How cells deal
Ex. Cells in a fluid like blood not in water – concentrations are equal
Plants and bacteria – cell wall keeps cell from exploding even under high osmotic pressure but they are very vulnerable
Pump it out
Ex. Unicellular organisms – paramecium – contractile vacuole – pumps it out

31. Facilitated Diffusion
Passive transport
Movement occurs from greater to lesser conc.
Need a concentration gradient
Molecules brought in by a carrier protein
Fast, specific
Facilitates or helps

33. Active Transport – 2 types
Needs energy
Move materials against a concentration gradient
Lesser to greater conc.

34. 1. Protein Pumps Pump molecules into the cell  Ca, K, Na Need energy
Sodium potassium pump

35. 2. Endocytosis (In)
Process of taking food into the cell by surrounding it with the cell membrane
Brings in large molecules, clumps of food and whole cells
Two Types
Phagocytosis – large particles
Pinocytosis – liquid, small particles
Exocytosis – large molecules out of cell - exit

37. The End