1. Structure Fits Function The Plasma Membrane
3 parts

3. Structure Phospholipid Bilayer – lipid (glycerol and 3 fatty acids)
Lipids make up fatty acid tails and are hydrophobic (afraid of water)
Phosphates are circular in shape and are hydrophilic (love water)

5. Structure
2. Proteins
Transport proteins allow needed substances or waste material to move through the plasma membrane
Chemical Markers (cell surface identity marker)– help cells to identify each other
Cell Signaling (cell surface receptor) – messages from outside of cell are communicated to inside

6. Structure 2. Proteins Click here video on cell membrane
Link to protein molecules

7. Structure Cholesterol: (found in animals)
lipid gives stability to the membrane

8. Structure Fluid Mosaic Model
Fluid refers to the movement of the phospholipids inside the membrane
Mosaic refers to the pattern the proteins create that are moving among the phospholipids

10. Function Protects inside of cell, provides a boundary
Plasma Membrane – job  to maintain homeostasis in the cell!
Selectively Permeable - Membrane allows certain molecules to pass through while keeping others out
Permeable – pass through
Selective - chooses

11. Transport across the membrane

12. Cell transport Movement of material across the plasma membrane
In solution
Solute  particles that are dissolved (Kool aid or salt or sugar)
Solvent  the substance in which the solute dissolves (water)

13. Concentration Amount of solute in a solution. (Think Kool-Aid)
High Concentration = lots of solute
Low Concentration = low amount of solute

14. Concentration Gradient
Simply means there is a difference in concentration.

15. Passive Transport
Requires no energy
Moves with the concentration gradient across the cell membrane, move from an area of high concentration to low concentration
Passive Transport keeps the cell in
equilibrium

16. Passive Transport Three types of Passive Transport:
Diffusion (oxygen and Carbon dioxide)
Osmosis (water)
3. Facilitated Diffusion transport of large molecules by a channel protein (glucose)
- small molecules can go across the membrane but large ones need help

17. Diffusion
Particles Travel
HIGH Low
Movement of particles from an area of high concentration to an area of low concentration
Driven by: Concentration Gradient (a difference in concentration over a given space.)
Equilibrium – Molecules are equal throughout.
Result: Equilibrium

18. High
concentration
Concentration gradient
Low
concentration
The greater the concentration gradient
the faster the molecules move

19. Diffusion

20. Will salt diffuse into or out of the cell?
Diffusion
3% salt
16% salt solution
Will salt diffuse into or out of the cell?

21. Will salt diffuse into or out of the cell?
Diffusion
3% salt
16% salt solution
Will salt diffuse into or out of the cell?

22. OSMOSIS Diffusion of water
Passive movement of water from high concentration to low concentration across a membrane

23. Which side needs to be diluted?
So water will go to side?
More water on side A because fewer particles

24. Water will move to side?
Why?

25. Selectively permeable membrane
5% sugar solution
20% sugar solution
80% water
95% water
Low
High
Selectively permeable membrane

26. **Cell will stay the same!!
Isotonic: (ISO means equal) the concentration of dissolved material is equal inside and outside the cell.
O S M O T I C S O L U T I O N S
70% Water
30% Salt
Cell
water
**Cell will stay the same!!

27. Hypertonic: Concentration of dissolved material is higher outside the cell than inside.
O S M O T I C S O L U T I O N S
80% Water
20% Salt
50% Water
50% Salt
Cell
water
**Cell will Shrink.

28. Hypotonic: (Hypo means under or below) Concentration of dissolved material is lower outside the cell than inside the cell.
O S M O T I C S O L U T I O N S
50% Water
50% Salt
90% Water
10% Salt
Cell
water
**Cell will Swell.
Helpful Reminder: Hypo (Cell Swells) is like Hippo (large hippopotamus)

29. Isotonic solution
RBC
Blood plasma
No Change

31. Hypotonic Solution
RBC
Why does the RBC increase
In size?
Pure water

33. Hypertonic Solution
RBC
Very salty water
Why has the RBC shriveled up?

35. C E L L O S M O S I S 3% solute 7% solute 4% solute 8% solute
Hypotonic
Hypertonic
Isotonic
Swells
Shrivels
Stays the same
Swells, could burst
Animals homeostasis in
out
equal
3% solute
7% solute
4% solute
Plant
Animal
Water Flows
97% water
93% water
96% water
Cell
8% solute
2% solute
4% solute
92% water
98% water
96% water
Write the % of water in each cell and solution.
Draw an arrow to show water movement

36. Turgor Pressure: water pressure in the plant cell that causes the cell membrane to press against the cell wall. It occurs in a hypotonic solution.
Plasmolysis – loss of water from a plant cell, causing pressure to drop in the cell and the cell membrane will shrink. It happens in a hypertonic solution.
Paramecium – contain contractile vacuoles to pump out excess water.

37. Active Transport Requires energy
Moves against concentration gradient from low concentration to high concentration
Three types of Active Transport:
1. Carrier proteins pump particles across the membrane using energy (energy, protein, and against the concentration gradient)
Which way would the particles flow if it was passive transport?
Which way would the particles be pumped if it was active transport?
What would the result be if active transport is used? A B
From side A to side B
From side B to side A
Unequal Concentration

39. Three types of Active Transport: (cont.)
2. Endocytosis- process by which materials are engulfed by the cell Endo: into cell a. Pinocytosis – cells bringing in fluids b. Phagocytosis – cells bringing in food 3. Exocytosis – process of materials leaving the cell Exo = Exit