1. Cell Transport Lecture #11 Ms. Day Honors Biology

2. REMEMBER: the cell membrane is selectively (semi-) permeable
Cell Transport
Means moving things INTO and OUT of the cell
Cells need to take in
Food, gases, water
Get rid of waste products
Release hormones and enzyme
REMEMBER: the cell membrane is selectively (semi-) permeable

3. REVIEW… Permeability and Cell Transport
Hydrophobic (non polar) molecules
Can mix with lipids (non polar regions)
can pass through membrane easily
Ex: CO2, O2, other small nonpolar things
Hydrophilic (Polar) molecules
Can NOT mix with lipids
Lipid INsoluble
Do not cross membrane easily
Ex: Na+, Cl- , Glucose/other polar or charged things

5. Types of Cellular Transport
high
low
Weee!
Passive Transport
cell does NOT use energy
Diffusion/Osmosis
Facilitated Diffusion
Active Transport
cell DOES use energy
Protein Pumps
Endocytosis
Exocytosis
high
low
This is going to be hard!

6. Types of Passive Transport
Diffusion= molecules (of ANY type..gas, liquid or solid) move from area of HIGH [ ] to lower [ ]
A “net” movement
“net” means OVERALL
Ex: Perfume, tea, food coloring in water

7. DIFFUSION Molecules move DOWN its OWN concentration gradient
difference in amount of a substance from one area to another
No chemical work (ATP energy) is used

8. Substances diffuse down their OWN concentration gradient
Figure 7.11 B
(b)
Net diffusion
Equilibrium

9. Effects of Osmosis on Water Balance
Diffusion of water across a semipermeable membrane
Water molecules move from MORE water to LESS water

10. Vocabulary Reminder... Solute Solvent Solution “Like mixes with like”
A substance that is dissolved
Solvent
A substance that is doing the dissolving of another substance
Solution
A uniform mixture of 2+ things
“Like mixes with like”
Nonpolar things mix w/ other nonpolar things
Polar things mix w/ other polar things

11. Amount of solutes and water is the same on both sides of a membrane
3 Different Types of Solutions ** compare solutions OUTSIDE cell to inside cell
1. Isotonic solution
Amount of solutes and water is the same on both sides of a membrane
“iso-” means “same”
There will be NO net movement of water
Cell does not change in size

12. ISOTONIC SOLUTION
Result: Water moves equally in both directions and the cell remains same size! (Cell is in “Dynamic Equilibrium”)

13. The cell will lose water and shrivel or wilt
2. Hypertonic solution
Amount of solutes is greater on one side of a membrane compared to the other side
“hyper” means more
high [solute]
[ ] = concentration of
The cell will lose water and shrivel or wilt

14. HYPERTONIC SOLUTION
Result: Water moves from inside the cell into the solution: Cell shrinks!

15. 3. Hypotonic solution
Amount of solutes are less on one side of the membrane compared to the other side
“hypo” means “less”
low [solute]
Also, think “hypo” is “low” meaning “low” solutes SURROUNDING cell
The cell will gain water and swell (and maybe burst)
“Hypo”
rhymes
with
LOW!!!

16. HYPOTONIC SOLUTION
Result: Water moves from the solution to inside the cell): Cell Swells and might burst

17. Osmosis Animations for isotonic, hypertonic, and hypotonic solutions

18. REVIEW…Types of Passive Transport
DOES NOT require ATP energy
Moves DOWN (WITH) [ ] gradient
Kinetic energy drives movement
#2 Active Transport
DOES require chemical energy (Ex: ATP)
Moves AGAINST its [ ] gradient

19. 2 Types of PASSIVE TRANSPORT
GOES DOWN CONCENTRATION GRADIENT (no ATP needed)
Molecules move HIGH [ ]low [ ]
1. SIMPLE DIFFUSION
**INCLUDES DIFFUSION
Uses NO membrane proteins
Examples: CO2, O2
2. FACILITATED DIFFUSION
needs a little “help”
Uses help of channel or carrier proteins
Examples: H2O, glucose

20. 2 Types of PASSIVE TRANSPORT
2. FACILITATED DIFFUSION
needs a little “help”
Uses help of channel or carrier proteins
GOES DOWN CONCENTRATION GRADIENT (no ATP needed)
Moves POLAR molecules  can NOT easily pass through HYDROPHOBIC region of membrane.
Example: ions, smaller polar molecules (ex: sugar)

21. Aquaporins water is polar but very small
It can pass easily through membrane
uses aquaporins
Oh…now
I get it!
EXTRACELLULAR
FLUID
AQUAPORIN
Channel protein
Water
CYTOPLASM

22. Channel proteins -Provide “tunnels”
Channel Proteins animations
Channel proteins -Provide “tunnels”
Figure 7.15
EXTRACELLULAR
FLUID
Channel protein
Solute
CYTOPLASM
A channel protein (purple) has a channel through which
water molecules or a specific solute can pass.
(a)

23. Carrier proteins -Undergo a subtle change in shape “carry” solute across the membrane

24. 2 Types of Passive Transport

25. Active transport Uses energy
Moves solutes against their [ ] gradients across the cell membrane
Energy required  usually ATP
Carrier proteins are used…NEVER channel proteins
Ex: protein pumps

26. Passive vs. Active Transport
Figure 7.17

27. Another type of transport = Bulk Transport
Occurs by exocytosis and endocytosis
BOTH MOVE “BIG” AMOUNTS OF STUFF in OR out OF THE CELL

28. Exocytosis In exocytosis
Transport vesicles move to the plasma membrane, fuse with it, and release their contents
“exo-” means “exit”
Ex: hormone excretion; nerve cells and transmitters; removal of wastes

30. Endocytosis In endocytosis
Cell takes in molecules by forming new vesicles from the plasma membrane
“endo-” means “enter”

31. 2 types of Endocytosis 1. Phagocytosis 2. Pinocytosis “cell eating”
Cell engulfs SOLIDS into vesicle & “digests” it
2. Pinocytosis
“cell drinking”
Cell engulfs LIQUIDS into vesicle & “digests” it

32. http://highered. mcgraw-hill

33. Endocytosis and Exocytosis Animations

34. REVIEW ANIMATIONS
Excellent Review all Passive (simple/facilitated diffusion) and Active Transport 
No verbal explanation…you have to read the tutorial!