1. Do Now
Welcome back! I hope you had a wonderful, relaxing holiday break! 
What is the role of the cell membrane?
How do you think it is able to perform this function?

2. Membrane Structure and Function
Chapter 5

3. Objectives To identify the components of the cell membrane
To explain what role each macromolecule has in creating the membrane structure

4. What does the membrane do?
Maintains an internal environment that is different from the external environment.
Regulates what molecules enter and exit the cell
Membranes are composed of a phospholipid bilayer

5. Phospholipid Bilayer Lets break down the word! Phospho-phosphate group
Lipid-Fat
Bilayer- 2 layers
**Unsaturated fatty acid tails have kinks in their tails to prevent them from being packed tightly together.

6. Phospholipid Bilayer
The phospholipid bilayer is said to be a “Fluid Mosaic Model”
Mosaic= composed of diverse pieces embedded in the framework.
Can also refer to the variety of functions provided by these pieces
Fluid= these pieces can drift about in the membrane

7. Selective Permeability
Controls the movement of substances in and out of the cell
Controls AMOUNT of substances entering and leaving the cell
Fish net analogy

8. POGIL
This activity is an introduction of this chapter and will cover a LOT of material. We will spend more time on each section so don’t worry if you are confused, however please call me over if you have any questions!

9. Do Now Please take out your POGIL activity!
What are the types of transport that the POGIL revealed to you?
How were they similar? How were they different?

10. Proteins Purpose: Types: Provide structure/framework
Provide channels for transport
Enzyme Activity
Receptors
Types:
Peripheral (surface)
Integral (Transmembrane)

11. Carbohydrates
Attached to proteins (glycoproteins) or attached to phospholipids (glycolipids)
Help cell identify chemical signals (cell to cell recognition)
Ex. Help disease-fighting cells recognize harmful cells

12. Cholesterol Stabilizes membrane
Prevents fatty acid tails from sticking together to keep the fluidity

14. Types of transport 1. Passive Transport 2. Active Transport
Requires NO energy
Molecules move down a concentration gradient
2. Active Transport
Requires energy
Molecules go against the concentration gradient

15. What is diffusion?
Diffusion-Movement of molecules from High concentration to Low Concentration by random motion (Moves down its concentration gradient)
Requires no energy
High Concentration
Low Concentration

16. Things that Affect the speed of Passive Transport
1. Heat- Hotter faster
2. Size – Bigger slower
3. State of Matter
Solid- Slow
Liquid – Fast
Gas- Fastest

17. Balanced Concentration
Diffusion continued…
Mixing continues until concentrations are the same in all areas
Dynamic Equilibrium-continues movement but NO NET overall change.
Balanced Concentration

18. Diffusion Video

19. Diffusion across the plasma membrane
*Cells also need ions and small molecules to perform cellular functions
(Ex. Ions and Sugars)
(Ex.H2O, O2, CO2)
T.P
Large and/or Charged- Transport Protein
Small and/or non-polar molecules

20. Facilitated Diffusion
Most substance cannot readily pass through the membrane.
Facilitated diffusion: Movement of materials across the plasma membrane using proteins (down concentration gradient)
Channel Proteins
Carrier Proteins

21. Types of Transport Proteins
Channel Proteins-
Pores that allow charged ions to pass through the membrane
Carrier (Gated) Proteins-
Change shape to help molecules pass through the membrane

22. Do Now
Looking at the beakers below, identify the picture that would match the descriptions.
A. Dissolved solute
B. Only Solute
C. An Uniform Mixture, Solution
D. Moving Solute Molecules
E. Shows 2 areas that show a difference in solute amount

23. Passive Transport Lab
Problem: Which solute molecules can pass through the membrane using passive transport?
3 Solutions:
Glucose
Starch
Iodine

24. Passive Transport Cell Model Set up
Post Lab
Passive Transport Cell Model Set up
This is after the dialysis bag that was filled with a glucose and starch solution looked like after 60 minutes.

25. Passive Transport Cell Model Setup
This is what the setup looked like after 24 hours.

26. The Benedict’s Solution Result
This is a tube of beaker solution and Benedict’s solution. Note the orange color that looks like carrot juice. Yum, yum!

27. Diffusion of Water- OSMOSIS
Water always flows via osmosis from HIGH water concentration to LOW water concentration through a semi permeable membrane.
Can move right through the phospholipids from high to low concentration (slow process)
Aquaporins- Integral membrane proteins that allow rapid diffusion of water into and out of cells

28. Osmosis Which container has more water in it?

29. Tonicity
A term that describes the ability of a solution to cause a cell to gain or lose water
Many organisms are able to maintain water balance within their cells by osmoregulation
This process prevents excessive uptake or excessive loss of water.
Plant, prokaryotic, and fungal cells have different issues with osmoregulation because of their cell walls.

30. Cellular Structure and Function
Isotonic Solution
Water and dissolved substances diffuse into and out of the cell at the same rate.
Plant Cell
Blood Cell
11,397x

31. HypOtonic Solution Solute concentration is higher inside the cell.
Water diffuses into the cell, cell swells/bursts
Plant Cell
Blood Cell
13,000x

32. Osmosis- diffusion of water across a membrane
Water always flows vis osmosis from HIGH water concentration to LOW water concentration
This cell Bursts!
22% Salt
45% Salt
H2O

33. Hypertonic Solution Solute concentration is higher outside the cell.
Water diffuses out of the cell, cell shrivels
Plant Cell
Blood Cell
13,000x

34. Osmosis- diffusion of water across a membrane
Remember: Water always flows via osmosis from HIGH water concentration to LOW water concentration This cell would shrink!
H2O
22% Salt
5% Salt

36. 3 Types of Solutions Cell in ________ Solution
H2O
H2O
H2O
For each solution, determine if the solute concentration of the solution is high, the same, or low as compared the cell.

37. Real life osmosis examples
Your garden is infested with slugs so you go around pouring salt on them
What type of solution is this salt?
What is going to happen to the cells of the slug? (Don’t do this to the poor slugs )

38. Real life osmosis examples
A salt water fish is put into a freshwater aquarium.
What type of solution is the freshwater?
What is going to happen to the cells of the fish?

39. Important Vocab…
Plasmolysis: State where plant cells shrink in hypertonic environment (animal cells= “crenation”)
Plant
Animal

40. Important Vocab…
Flaccid: State where a plant cell is placed in isotonic solution
Plant
Animal

41. Important Vocab…
Cytolysis: State where cells Burst in hypotonic environment
Turgid: State where plant cells swell in hypotonic solutions
Creates Turger Pressure in plants
(animal cells= Lyse)
Plant
Animal

42. Active Transport
Specific protein can pump molecules across the membrane
Usually in opposite direction of diffusion (Low concentration to high concentration)
Against the concentration gradient
Requires ENERGY (ATP)

43. Sodium Potassium Pump Type of Active Transport
Moves three Na+ ions out of the cell and two K+ ions into the cell

44. Sodium Potassium Pump: Video

45. Transport of Large Molecules
Usually Transported by Vesicles
Endocytosis-Into the cell
Phagocytosis- Engulfment of particles into vesicles.
Pinocytosis- Engulfment of fluids into small vesicles
Receptor-mediated- interact with specific protein to initiate vesicle formation.
Exocytosis-Exiting the cell