1. Introductory Questions (Lab)
Suppose you have an artificial cell that was permeable to monosaccharides and impermeable to disaccharides. What would happen to the cell if it had 0.80 M maltose and 0.85 M fructose in it and was placed in a solution containing 0.45 M glucose, 0.65 M fructose, and 0.40 M sucrose.
a) Which direction would the water flow?
b) Which area has a higher water potential?
c) What would happen to the concentration of the maltose inside the cell (increase, decrease, remain the same)?
What is the ionization constant (i) for sucrose?
Determine the “C” value for your potato cores. (guide sheets)
Graph your results:
% change in mass vs. sucrose molarity within the beakers
(guide sheets)

2. Introductory Questions #3
1) What purpose do vesicles serve in the cell?
2) Name all of the organelles that are a part of the endomembrane system.
3) Explain how the rough ER is different from the smooth ER,
How is a lysosome different from a peroxisome?
How is the basal body of the flagella similar to centrioles? (see pg. 115)
Name the three parts of the cytoskeleton. Which protein fiber is the smallest? Which is the largest?
Which intercellular junction is composed of protein surrounding a pore allowing for ions, sugars, etc. to pass from one cell to the next? Name a similar structure in plants.
What does ECM stand for? Name the most abundant glycoprotein found in the ECM. What purpose does it serve?

3. Introductory Questions #
What purpose do protein Kinase enzymes serve in the signal transduction process? (Ch. 11 pgs )

4. Dialysis Tubing Experiment

5. Chapter 7~ Membrane Structure & Function

6. Introductory Questions #4
Name the major molecules that make up the cell membrane. How thick is the membrane?
How does the fluid mosaic model proposed by Singer & Nicholson (1972) compare with the Daveson & Danielli (1935) model?
Briefly explain how the membrane remains fluidic in lower temperatures?
What did the freeze fracture process and electron microscope reveal about the membrane?
How does cholesterol act as a “buffer” for the membrane? How does a hypotonic solution differ from a hypertonic solution?
What are the three forms of endocytosis? Explain how they are different.

7. Introductory Questions #5
What is the charge range difference across the membrane? Which side is positive and which side is negative? Why is this the case?
How is diffusion different from facilitative diffusion?
Name some factors that can affect diffusion rates of molecules.
Name the ions used to show how active transport works in a the cell membrane. What role does ATP play during this process?

8. Membrane Structure-Two Models Proposed
Amphipathic Lipids~ hydrophobic & hydrophilic regions
Singer-Nicholson: fluid mosaic model
proposed in 1972
(Current model)

9. The Phospholipid Bilayer
The heads face outward and the tails face inward
In water, phospholipids form a stable bilayer
Water
Hydrophilic heads
Hydrophobic tails
Water
Figure 5.11B

10. Closer View of the Cell Membrane

11. Membrane Structure Approx. 10 nm thick Phospholipid Bilayer
-Amphipathic molecules
-Saturated and Unsaturated lipids
Proteins: integral &* peripheral
Cholesterol-acts as a temperature buffer

12. Membranes organize the chemical activities of cells
Membranes organize the chemical reactions making up metabolism  
Cytoplasm
Figure 5.10

13. Function of the Plasma Membrane
They control the flow of substances into and out of a cell
Membranes are selectively permeable
**Small, Nonpolar molecules easily pass through the membrane: O2, CO2, Hormones, Steroids
vs.
**Large, Charged do not pass through easily and must be helped in. These molecules would include:
C6H12O6 , Proteins, and Ions
Membranes regulate chemical reactions and can hold teams of enzymes that function in metabolism

14. A Phospholipid

15. Membrane Phospholipids
Phospholipids are the main structural components of membranes
They each have a hydrophilic head and two hydrophobic tails
Head
Symbol
Tails
Figure 5.11A

16. Membrane Structure - 2nd Look
Phospholipids~ membrane fluidity
Cholesterol~ membrane stabilization
“Mosaic” Structure~
Integral proteins~ transmembrane proteins
Peripheral proteins~ surface of membrane
Membrane carbohydrates ~ cell to cell recognition; oligosaccharides (cell markers); glycolipids; glycoproteins

17. Phospholipid Fluidity

18. Fluidic Nature of the Membrane
To function properly:
Lipids must be in a state of optimal fluidity
Too much fluidity weakens the membrane
-not enough cholesterol
-too many unsaturated phospholipids
Also, the membrane cannot be too rigid because transport through the membrane is inhibited
Temperature changes can severely effect the membrane. HOW?

19. Mouse-Human Hybrid Cell (Pg. 108)
David Frye & Micheal Edin (1970)

20. Freeze Fracture Method (Pg. 126)

22. Typical (integral)Transmembrane Protein

23. Proteins: Six Major Functions Observed- Pg. 128)
C,D A G F G B

24. Lateral Transfer Across the Membrane
See Pgs (Ch. 11- Cell Communication)
Begins w/ signaling molecule called a Ligand
Ligands-examples are hormones & proteins
Involves several proteins:
Receptor (1st messenger) binds w/the ligand
Protein Kinases: an enzyme that transfers phosphate groups from ATP to a protein (uses ATP & move phosphates)
G proteins & Adenylyl cyclase
Cyclic AMP: 2nd messengers

25. Lateral Transfer of Information Across the Membrane
Adenylyl Cyclase
Ligand
Enzymatic Rxns
G Protein
Receptor
cAMP
2nd messenger
Figure 5.13

26. Passive transport: Diffusion across a membrane
In passive transport, substances diffuse through membranes without work by the cell
They spread from areas of high concentration to areas of lower concentration
Molecule of dye
Membrane
EQUILIBRIUM
EQUILIBRIUM
Figure 5.14A & B

27. Membrane Traffic - (Pg. 132)
Diffusion~ tendency of molecules to move from
areas of high concentration to areas of low. Concentration gradient
Passive transport~ diffusion of a substance across a biological membrane
Osmosis~ the diffusion of water across a selectively permeable membrane

28. Osmosis is the passive transport of water
Hypotonic solution
Hypertonic solution
In osmosis, water travels from an area of lower solute concentration to an area of higher solute concentration
Selectively permeable membrane
Solute molecule
HYPOTONIC SOLUTION
HYPERTONIC SOLUTION
Water molecule
Selectively permeable membrane
Solute molecule with cluster of water molecules
NET FLOW OF WATER
Figure 5.15

29. Two Models of Facilitated Diffusion http://www. wiley

30. Dialysis Tubing Experiment

31. Introductory Questions #4
Name the major molecules that make up the cell membrane. How thick is the membrane?
How does the fluid mosaic model proposed by Singer & Nicholson (1972) compare with the Daveson & Danielli (1935) model?
Briefly explain how the membrane remains fluidic in lower temperatures?
What did the freeze fracture process and electron microscope reveal about the membrane?
How does cholesterol act as a “buffer” for the membrane? How does a hypotonic solution differ from a hypertonic solution?
What are the three forms of endocytosis? Explain how they are different.

32. Introductory Questions #
What did the freeze fracture process and electron microscope reveal about the membrane?
What purpose do protein Kinase enzymes serve in the signal transduction process? (Ch. 11 pgs )
How is diffusion different from facilitative diffusion?
Name some factors that can affect diffusion rates of molecules.
Name the ions used to show how active transport works in a the cell membrane. What role does ATP play during this process?
What is the charge range difference across the membrane? Which side is positive and which side is negative?

33. Water balance between cells and their surroundings is crucial to organisms
Osmosis causes cells to shrink in a hypertonic solution and swell in a hypotonic solution
The control of water balance (osmoregulation) is essential for organisms
ISOTONIC SOLUTION
HYPOTONIC SOLUTION
HYPERTONIC SOLUTION
ANIMAL CELL
(1) Normal
(2) Lysing
(3) Shriveled
Plasma membrane
PLANT CELL
Figure 5.16
(4) Flaccid
(5) Turgid
(6) Shriveled

34. An Artificial Cell Permeable to: monosaccharides & water Impermeable to: Disaccharides

35. Active Transport (Pg. 135)

36. Active transport in two solutes across a membrane
FLUID OUTSIDE CELL
Phosphorylated transport protein
Active transport in two solutes across a membrane
Transport protein
First solute 1
First solute, inside cell, binds to protein 2
ATP transfers phosphate to protein 3
Protein releases solute outside cell
Second solute 4
Second solute binds to protein 5
Phosphate detaches from protein 6
Protein releases second solute into cell
Figure 5.18

37. Common Type of Active Transport
Utilizes ATP and a protein
Moves substances against the concentration gradient
(Low to High)
Typical example is:
Sodium-potassium pump
(Observed in nerve cells)

38. Generating a Membrane Potential
Membrane potential: a charge difference across the membrane
Most commonly seen in nerve cells (sodium & potassium pump) – see pg 135
Achieved through actively pumping ions on one side of the membrane. (Na+ and K+)
All cells have a potential with a slight negative charge on the inside a positive charge on the outside. Why???

39. Specialized Transport
Transport proteins
Facilitated diffusion~ passage of molecules and ions with transport proteins across a membrane down the concentration gradient
Active transport~ movement of a substance against its concentration gradient with the help of cellular energy

40. Water Balance (pg. 133) Osmoregulation~ control of water balance
Hypertonic~ higher concentration of solutes
Hypotonic~ lower concentration of solutes
Isotonic~ equal concentrations of solutes
Cells with Walls:
Turgid (very firm)
Flaccid (limp)
Plasmolysis~ plasma membrane pulls away from cell wall

41. Endocytosis vs. Exocytosis
Endocytosis~ import of macromolecules by forming new vesicles with the plasma membrane
•phagocytosis
•pinocytosis
•receptor-mediated
Exocytosis~ secretion of macromolecules by the fusion of vesicles with the plasma membrane

42. Exocytosis and endocytosis transport large molecules
To move large molecules or particles through a membrane
a vesicle may fuse with the membrane and expel its contents (exocytosis)
FLUID OUTSIDE CELL
CYTOPLASM
Figure 5.19A

43. or the membrane may fold inward, trapping material from the outside (endocytosis)
Figure 5.19B

44. Three Types of Endocytosis

45. Material bound to receptor proteins
Three kinds of endocytosis
Pseudopod of amoeba
Food being ingested
Plasma membrane
Material bound to receptor proteins
PIT
Cytoplasm
Figure 5.19C

46. Harmful levels of cholesterol can accumulate in the blood if membranes lack cholesterol receptors
Phospholipid outer layer
LDL PARTICLE
Receptor protein
Protein
Cholesterol
Plasma membrane
Vesicle
CYTOPLASM
Figure 5.20

47. The plasma membrane of an animal cell
Glycoprotein
Carbohydrate (of glycoprotein)
Fibers of the extracellular matrix
Glycolipid
Phospholipid
Cholesterol
Microfilaments of the cytoskeleton
Proteins
CYTOPLASM
Figure 5.12