1. Chapter 7-3 Cell Boundaries
Part 1

2. Focus Questions
What are the main functions of the cell membrane and cell wall?
What happens during diffusion?
What is osmosis?

3. “I can…” statements
I can... Describe the function of the cell membrane.
I can… Compare and contrast active and passive transport
I can… differentiate between hypotonic, hypertonic, and isotonic.

4. 1. Cell Membranes: ALL cells have one!
A. Outer boundary of the cell
B. Functions
1) Separates a cell from other cells
2) Protection and support
3) Controls what enters and exits the cell, to maintain homeostasis

6. C. Structure: (described as) Lipid Bilayer
1) 2 layers of phospholipids
a) polar head: forms outside of bilayer
Described as hydrophilic: water loving, attracts water
b) non-polar tail: forms inside of bilayer
Described as hydrophobic: water fearing, avoids water
(polar)HEAD
Hydrophilic
(nonpolar) TAIL
Hydrophobic

8. 2) Proteins with carbohydrate chains are wedged between Phospholipid molecules.
3) Proteins act as pores, channels or pumps to move substances into or out of cell.
4) Carbohydrates are markers which are used for cell
identification.

9. D. Selectively permeable: allows certain substances to pass through
The structure allows it to be selective.
Protein pores allow small thing insoluble in lipids pass( Ex. H20)
Ex. Glucose can pass through
Things soluble in Lipids can pass (Ex. Alcohol)

10. Molecules can pass through IF:
They are soluble (able to dissolve) in lipids, they can easily pass through bilayer (ex. Alcohol, CO2, O2, steroids)
They are NOT soluble (unable to dissolve) in lipids (water, glucose, amino acids, ions:
May be small enough to get through protein pores (ex. water)
May be able to go through a protein channel (ex. Glucose)
May be able to get pushed through by a protein pump Ex. Na+(sodium ion), K+(potassium ion)

11. Examples of substances that need to pass into cell:
1. water 2. glucose 3.oxygen
Examples of substances that need to pass out of cell:
1. carbon dioxide water

12. 1) Plants 2) Algae 3) Bacteria 4) Fungi
Cell Walls
A. Found in:
1) Plants 2) Algae 3) Bacteria 4) Fungi
(Have both cell membrane AND cell wall)
B. NOT IN ANIMAL CELLS
C. Function: EXTRA Support and protection, and gives strength to cells
D. Composed of fibers of carbohydrates:
1. Cellulose in _____________
2. Chitin in _______________
3. Peptidoglycan in ___________________
Plants
Fungi
Eubacteria

13. REVIEW QUESTIONS
How does water move through the cell membrane? _______________
What does semi-permeable mean? ___________________________________
What molecule is the lipid bilayer made of? ___________
Which part is polar? _______Which is nonpolar?_________
How does one cell recognize that a cell is part of that tissue or organ? _____________
What is a substance that is soluble in lipids, that would pass through the lipid bilayer of the cell membrane easily?_______
True or False: All cells have cell walls? ______________
Through PROTEIN pores
Only allows certain substance through
Phospholipid
Head
tail
Carbohydrate chain
Alcohol
False –animal cells don’t

14. Chapter 7-3 Notes Part 2
Types of Transport

15. TRANSPORT CAN BE EITHER

16. Passive Transport DOES NOT REQUIRE ENERGY!!! On top of the hill
DRAW
Passive Transport
On top of the hill
Movement of molecules from areas of high concentration to areas of lower concentration.
DOES NOT REQUIRE ENERGY!!!
high
low
Weeee!!!

17. OR

18. This is gonna be hard work!!
DRAW
Active Transport
Bottom of the hill
Movement of molecules from areas of low concentration to areas of high concentration.
REQUIRES ENERGY!
high
low
This is gonna be hard work!!

19. Animations of Active Transport & Passive Transport
Types of Passive Transport
cell does not use energy
Diffusion
Facilitated Diffusion
Osmosis
All 3 types of PASSIVE transport occur until equilibrium is reached.
Equilibrium:
when the concentration of a solute is the same throughout a closed system. (i.e. Inside and outside of a cell.)

20. Types of Active Transport cell uses energy
Protein Pumps
Endocytosis
Exocytosis

21. Three Types of Passive Transport Defined
Ch 7-3 Notes Part 3
Three Types of Passive Transport Defined

22. 1. Diffusion: movement of molecules FROM areas of HIGH concentration TO areas of LOW concentration through the lipid bilayer. Examples: Alcohol, CO2, O2

23. GO TO DIFFUSION ANIMATION

24. Simple Diffusion Animation

25. 2. Facilitated DiffusionB
Diffusion of specific particles through transport proteins found in the cell membrane Example:Glucose
Transport Proteins are specific – they “select” only certain molecules to cross the membrane
Transports molecules that are large or insoluble in lipids.
Facilitated diffusion (Channel Protein)
Diffusion (Lipid Bilayer)
Carrier Protein

26. Osmosis animation
3. Osmosis
diffusion of water through a selectively permeable membrane.
a. Water moves from high concentration of (H2O)to low concentration(of H2O)
Water moves freely through special pores.
Solute (green) soluble in lipids.

27. Effects of Osmosis on Life
Cells cannot control the movement of water (Osmosis).
ii. If too much water moves into the cell it can burst (die). If too much water moves out it can shrivel up (die).

28. HOW DO SOLUTIONS AFFECT OSMOSIS???

29. Osmosis Animations for isotonic, hypertonic, and hypotonic solutions
Hypotonic: 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 into the cell. Osmotic pressure increases and causes the cell to grow until equilibrium is reached or the cell bursts. Hint: HYPO=HIPPO(grow)

30. Osmosis Animations for isotonic, hypertonic, and hypotonic solutions
Hypertonic Solution
Hypertonic: The solution has a higher concentration of solutes and a lower concentration of water than inside the cell. (High solute; Low water)
Result: Water moves out of the cell into the solution: Cell shrinks/shrivels.

31. Isotonic Solution(Iso=Equal)
Osmosis Animations for isotonic, hypertonic, and hypotonic solutions
Isotonic Solution(Iso=Equal)
Isotonic: The concentration of solutes and water in the solution is equal to the concentration of solutes and water inside the cell.
Result: Water moves equally in both directions (Dynamic Equilibrium) and the cell remains same size!

32. 2 3 1 What type of solution are these cells in? Hypertonic Isotonic
TOO MUCH
OSMOTIC
PRESSURE!!! 2 3 1
Hypertonic
Isotonic
Hypotonic
*Which of these solutions do you think is used in an IV?

33. How Organisms Deal with Osmotic Pressure
Paramecium (protist) removing excess water video
How Organisms Deal with Osmotic Pressure
1. A protist, like paramecium, has contractile vacuoles that collect water flowing in and pump it out to prevent them from over- expanding.
Contractile Vacuole:

34. 2. Bacteria and plants have cell walls that keep the membrane from bursting when osmotic pressure increases.

35. 3. Animal cells are bathed in blood
3. Animal cells are bathed in blood. Kidneys keep the blood isotonic by removing excess salt and water.

36. Part 4: Active Transport
Ch 7-3 Notes
Part 4: Active Transport

37. 1. Three Types of Active Transport
Protein Pumps
Endocytosis
Exocytosis

38. D. 3 Types of Active Transport
Sodium Potassium Pumps (Active Transport using proteins)
Protein Pumps –Require energy transport molecules across membrane.
Example: Ions such as Na+ and K+ in Sodium / Potassium Pumps, which are important in nerve responses.
Protein changes shape to move molecules: this requires energy!

39. Endocytosis: taking bulky material into a cell
a. Uses energy
b. Cell membrane folds in around food particle
“cell eating”
c. forms food vacuole & digests food
d. This is how white blood cells eat bacteria!

40. Endocytosis & Exocytosis animations
3. Exocytosis: Forces material out of cell in bulk
a. membrane surrounding the material fuses with cell membrane
b. Cell changes shape – requires energy
EX: Hormones or wastes being released from the cell
Endocytosis & Exocytosis animations
Exocytosis