1. The comings and goings of the cell…
Cell Transport
The comings and goings of the cell…

2. TEM picture of a real cell membrane.
About Cell Membranes
All cells have a cell membrane
Functions:
Controls what enters and exits the cell to maintain an internal balance called homeostasis
Provides protection and support for the cell
TEM picture of a real cell membrane.

3. About Cell Membranes (continued)
Structure of cell membrane
Lipid Bilayer -2 layers of phospholipids
Phosphate head is polar (water loving)
Fatty acid tails non-polar (water fearing)
Proteins embedded in membrane
Phospholipid
Lipid Bilayer

4. Fluid Mosaic Model of the cell membrane
Polar heads love water & dissolve.
Non-polar tails hide from water.
Carbohydrate cell markers
Proteins

5. About Cell Membranes (continued)
4. Cell membranes have pores (holes) in it
Selectively permeable: Allows some molecules in and keeps other molecules out
The structure helps it be selective!
Pores

6. Structure of the Cell Membrane
Outside of cell
Carbohydrate
chains
Proteins
Lipid
Bilayer
Transport
Protein
Phospholipids
Inside of cell
(cytoplasm)

7. Semipermeable Membrane
Small molecules and larger hydrophobic molecules move through easily.
e.g. O2, CO2, H2O

8. Semipermeable Membrane
Ions, hydrophilic molecules larger than water, and large molecules such as proteins do not move through the membrane on their own.

9. Types of Cell Transport

10. Types of Transport Across Cell Membranes
Passive Transport
Diffusion
Osmosis
Facilitated Diffusion
Active Transport
Pumps
Bulk Transport
high
low
Weeee!!!
high
low
This is gonna be hard work!!

11. Transport Concepts Passive vs. Active Passive Active
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Passive
Active

12. Concentration Gradient
The difference in concentrations on the two different sides of a membrane.
HIGH CONCENTRATION
Concentration: the amount of a substance in a particular area
WHICH WAY WOULD THE COWS LIKE TO GO?
LOW CONCENTRATION

13. (HighLow) Passive Transport NO ENERGY REQUIRED cell uses no energy
solute spread out from an area of high concentration to an area of low concentration.
(HighLow)
Three types
NO ENERGY REQUIRED

14. 3 Types of Passive Transport
Diffusion
Facilitative Diffusion – diffusion with the help of transport proteins
Osmosis – diffusion of water

15. Diffusion Passive Transport (no energy)
Solute move from area of HIGH to LOW concentration
Diffusion continues until all solutes are evenly spaced (equilibrium is reached)

16. Diffusion of Liquids

17. Diffusion through a Membrane
Cell membrane
Solute moves DOWN concentration gradient (HIGH to LOW)

18. Facilitated Diffusion
Passive: No Energy
Use Proteins to move substances
High to Low
Most substances that the cell needs can not diffuse directly through the cell membrane.
Ions, sugar, etc.
Facilitated Diffusion
Transport Proteins are specific – they “select” only certain molecules to cross the membrane
Transports larger or charged molecules

19. Passive Transport: Facilitated Diffusion
Glucose
molecules
Cellular Transport From a-
HIGH
High Concentration
Cell Membrane
Low Concentration
Protein
channel
Low
Transport Protein
Through a 

20. Osmosis Passive: No Energy Movement of WATER
Moves from HIGH water concentration (low solute) to LOW water concentration (high solute)

21. Question Why did the level of water rise in the left column?
Passive Transport Recap

22. Background Knowledge
Hypo
Hyper
Iso

23. How does OSMOSIS affect life?

24. Hypotonic Solution
Hypotonic: The solution has a lower concentration of solutes and a higher concentration of water compared to inside the cell. (Low solute; High water)
Result: Water moves from the solution to inside the cell: Cell Swells and bursts open (cytolysis)!

25. Hypertonic Solution
Hypertonic: The solution has a higher concentration of solutes and a lower concentration of water compared to inside the cell. (High solute; Low water)
shrinks
Result: Water moves from inside the cell into the solution: Cell shrinks (Plasmolysis)!

26. Isotonic Solution
Isotonic: The concentration of solutes in the solution is equal to the concentration of solutes inside the cell.
Result: Water moves equally in both directions and the cell remains same size! (Dynamic Equilibrium)

27. B C A What type of solution are these cells in? Hypertonic Isotonic
Hypotonic

28. How Organisms Deal with Osmotic Pressure
Paramecium (protist) removing excess water video
Bacteria and Plants: Cell Wall- Turgor Pressure
turgor pressure
Paramecium- Contractile Vacuole
contractile vacuole
Salt water fish pump salt out of their specialized gills so they do not dehydrate.
Animal cells are bathed in blood. Kidneys keep the blood isotonic by remove excess salt and water.

30. Plant Cell Osmosis
NORMAL
PLACED IN A HYPERTONIC SOLUTION…PLASMOLYSIS!

31. Quick Review

32. Cell in Isotonic Solution
10% NaCL 90% H2O
ENVIRONMENT
CELL
NO NET MOVEMENT
10% NaCL
90% H2O
What is the direction of water movement?
equilibrium
The cell is at _______________.

33. Cell in Hypotonic Solution
10% NaCL 90% H2O
CELL
20% NaCL
80% H2O
What is the direction of water movement?

34. Cell in Hypertonic Solution
15% NaCL 85% H2O
ENVIRONMENT
CELL
5% NaCL
95% H2O
What is the direction of water movement?

35. Practice Tonicity *Find a partner

36. Active Transport

37. Active Transport Can I get a little help? Requires ENERGY!
Energy in the form of ATP
Materials move AGAINST the concentration gradient
Types:
Na+/K Pump & H+ Pump
Bulk Transport using vesicles
Can I get a little help?

38. Sodium Potassium Pump
sodium, potassium pump

39. BULK TRANSPORT

40. Bulk Transport
Movement of large molecules or a large amount of materials using vesicles.
2 Types:
Exocytosis
Endocytosis
Pinocytosis
Phagocytosis

41. Vesicle
Membrane bound “sac” that transports materials into or out of the cell

42. EXOCYTOSIS
Movement of materials out of the cell
EXO=exit

43. ENDOCYTOSIS Movement of materials inside of the cell ENDO=enter
2 types
recap

44. PHAGOCYTOSIS
Cell “Eating”
A cell ingests a food particle

45. PINOCYTOSIS Cell “Drinking”
Ingestion of dissolved materials from extracellular fluid

46. recap bulk transport (both)