1. Membrane Transport

2. Cell or Plasma Membrane
Composed of double layer of phospholipids and proteins (phospholipid bilayer)
Surrounds outside of ALL cells
Controls what enters or leaves the cell
Living layer
Outside
of cell
Inside
(cytoplasm)
Cell
membrane
Proteins
Protein
channel
Lipid bilayer
Carbohydrate
chains
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Phospholipids
Heads contain glycerol & phosphate and are hydrophilic (attract water)
Tails are made of fatty acids and are hydrophobic (repel water)
Make up a bilayer where tails point inward toward each other
Can move laterally to allow small molecules (O2, CO2, & H2O to enter)
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4. Cell Membrane Proteins
Proteins help move large molecules or aid in cell recognition
Peripheral proteins are attached on the surface (inner or outer)
Integral proteins are embedded completely through the membrane
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6. The Cell Membrane is also referred to as the Fluid Mosaic Model
Molecules in cell membranes are constantly moving and changing
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7. Structures Of The Plasma Membrane
Phosphate Head: Made of a phosphate group (polar and attracts water)
Carbohydrate: Used for cell recognition
Membrane Protein: Transports large particles across the cell membrane
Cholesteral: Helps stabilize the phospholipids
Lipid Tails: Made of fatty acids (non-polar and does not attract water)

8. Diffusion
Movement of particles
From high
To Low

9. Diffusion
Concentration: the mass of solute (what's being dissolved) in a given volume of solvent (what’s doing the dissolving)
Equilibrium: the concentration throughout a solution is the same

11. Diffusion
● Concentration gradient: the difference in concentration across a barrier/membrane
● Because diffusion depends upon random particle movements, substances diffuse across membranes without requiring the cell to use energy

13. Osmosis Movement of water From high to low Across a selectively
permeable
membrane
-selects what moves in and out

14. Osmosis

15. Dynamic Equilibrium Equal concentrations are reached
Not the same volumes
Continued movement across the membrane
Not gain or loss

16. Osmosis
● Osmosis is the diffusion of water through a selectively permeable barrier. Water will tend to move across the membrane until equilibrium is reached, when this occurs the two solutions will be isotonic, the same.
● When a solution is more concentrated with solute it is said to be hypertonic, whereas a dilute (less concentrated) solution is said to be hypotonic.
Pre-AP do the potato experiment with salt water
Discuss osmotic pressure as a side discussion to the second question. For Pre AP may wish to perform potato lab with regular tap water and salt water.

17. Osmosis

18. Isotonic Solutions Iso- equal No change in concentrations
Water still moves
Same amount of water moves in as moves out
Both sides of membrane are the same

20. Hypertonic Solution Hyper- Over Out side of cell
More dissolved substance
Less water
Water moves out of cell

22. Hypotonic Solution Hypo- under Out side of cell Water moves into cell
Less dissolved substance
More water
Water moves into cell

24. Passive Transport Cell uses no energy From high to low Plasma membrane
Concentration
gradient

25. Facilitated Diffusion
Type of passive transport
Use transport
proteins
Channel proteins
Carrier proteins
Changes shape
From high to low

26. Facilitated Diffusion
● During facilitated diffusion molecules that would not normally be able to cross through the membrane, such as glucose, diffuse across the membrane through selected protein channels.
It is dependent upon the concentration gradient because it does not require the cell to expend any energy.

28. Active Transport Cell uses energy Against concentration gradient
From low to high
Carrier Proteins
Molecule binds with carrier protein
Energy then used to change shape
Molecule released on other side
Carrier protein returns to original shape

29. Active Transport
●The movement of material across a membrane and against a concentration gradient is called active transport.
Like facilitated diffusion this is carried out by protein channels in the membrane called transport proteins, however in this form of diffusion energy is expended in the process of “pumping” the material “uphill” against the gradient.

30. Active Transport
Molecule to
be carried
Molecule
being carried
Energy

31. Large Particle Transport
● Endocytosis is the process of taking material into the cell by means of enfolding's, or pockets, of the cell membrane. The pocket or enfold, once it has surrounded the molecule, then closes and breaks off from the membrane forming a vacuole. Two examples of endocytosis are phagocytosis (cell eating) and pinocytosis (cell drinking).
● Exocytosis works the opposite of endocytosis. It is a vacuole with material designated to leave the cell which joins with the cell membrane then releases its material outside of the cell.

32. Large Particle Transport (Exocytosis and Endocytosis)

33. Large Particle Transport
Not through membrane
Requires energy
Exocytosis- out

35. Large Particle Transport
Endocytosis- in

36. Types of Endocytosis
Pinocytosis: liquid (into) Phagocytosis: Solid (into)