1. Wednesday September 20, 2017 Bell Ringer
Copy and answer the following:
What is homeostasis?
Why is it important for the cell membrane to guard what enters and leaves the cell?

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Amoeba Sisters Video
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3. Thursday September 21, 2017 Bell Ringer
Copy and answer the following:
1. What process was being used by the
“cells” in yesterday’s lab?
2. Sketch a picture that shows how the
vinegar moved in the experiment.
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The Plasma Membrane
2/16/2019
The Plasma Membrane -
Gateway to the Cell
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G. Podgorski, Biol. 1010

5. Photograph of a Cell Membrane
The Plasma Membrane
2/16/2019
Photograph of a Cell Membrane
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G. Podgorski, Biol. 1010

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The Plasma Membrane
2/16/2019
Cell Membrane
The cell membrane is flexible and allows a unicellular organism to move
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G. Podgorski, Biol. 1010

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The Plasma Membrane
2/16/2019
Homeostasis
Balanced internal condition of cells
Also called equilibrium
Maintained by plasma membrane controlling what enters & leaves the cell
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G. Podgorski, Biol. 1010

8. Functions of Plasma Membrane
The Plasma Membrane
2/16/2019
Functions of Plasma Membrane
Protective barrier
Regulate transport in & out of cell (selectively permeable)
Allow cell recognition
Provide anchoring sites for filaments of cytoskeleton
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G. Podgorski, Biol. 1010

9. Functions of Plasma Membrane
The Plasma Membrane
2/16/2019
Functions of Plasma Membrane
Provide a binding site for enzymes
Interlocking surfaces bind cells together (junctions)
Contains the cytoplasm (fluid in cell)
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G. Podgorski, Biol. 1010

10. Structure of the Cell Membrane
The Plasma Membrane
2/16/2019
Structure of the Cell Membrane
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G. Podgorski, Biol. 1010

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Membrane Components
The Plasma Membrane
2/16/2019
Phospholipids
Proteins (peripheral and integral)
Cholesterol
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Carbohydrates (glucose)
G. Podgorski, Biol. 1010

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The Plasma Membrane
2/16/2019
Phospholipids
Make up the cell membrane
Contains 2 fatty acid chains that are nonpolar
Head is polar & contains a –PO4 group & glycerol
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G. Podgorski, Biol. 1010

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The Plasma Membrane
2/16/2019
FLUID MOSAIC MODEL
FLUID- because individual phospholipids and proteins can move side-to-side within the layer, like it’s a liquid.
MOSAIC- because of the pattern produced by the scattered protein molecules when the membrane is viewed from above.
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G. Podgorski, Biol. 1010

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The Plasma Membrane
Cell Membrane
2/16/2019
Polar heads are hydrophilic “water loving”
Nonpolar tails are hydrophobic “water fearing”
Makes membrane “Selective” in what crosses
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G. Podgorski, Biol. 1010

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The Plasma Membrane
2/16/2019
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G. Podgorski, Biol. 1010

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The Plasma Membrane
Cell Membrane
2/16/2019
The cell membrane is made of 2 layers of phospholipids called the lipid bilayer
Hydrophobic molecules pass easily; hydrophilic DO NOT
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G. Podgorski, Biol. 1010

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The Plasma Membrane
2/16/2019
Solubility
Materials that are soluble in lipids can pass through the cell membrane easily
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G. Podgorski, Biol. 1010

19. Semipermeable Membrane
The Plasma Membrane
Semipermeable Membrane
2/16/2019
Small molecules and larger hydrophobic molecules move through easily.
e.g. O2, CO2, H2O
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G. Podgorski, Biol. 1010

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The Plasma Membrane
Semipermeable Membrane
2/16/2019
Ions, hydrophilic molecules larger than water, and large molecules such as proteins do not move through the membrane on their own.
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G. Podgorski, Biol. 1010

21. Friday September 22, 2017 Bell Ringer
Copy and answer:
Based on the cell membrane activity yesterday, why do phospholipids form a bilayer in a cell membrane? Make sure to include the words polar, nonpolar, hydrophilic and hydrophobic.
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22. Types of Transport Across Cell Membranes
The Plasma Membrane
2/16/2019
Types of Transport Across Cell Membranes
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G. Podgorski, Biol. 1010

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The Plasma Membrane
2/16/2019
Simple Diffusion
Requires NO energy
Molecules move from area of HIGH to LOW concentration
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G. Podgorski, Biol. 1010

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The Plasma Membrane
2/16/2019
DIFFUSION
Diffusion is a PASSIVE process which means no energy is used to make the molecules move, they have a natural KINETIC ENERGY
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G. Podgorski, Biol. 1010

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The Plasma Membrane
2/16/2019
Diffusion of Liquids
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G. Podgorski, Biol. 1010

26. Diffusion through a Membrane
The Plasma Membrane
2/16/2019
Diffusion through a Membrane
Cell membrane
Solute moves DOWN concentration gradient (HIGH to LOW)
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G. Podgorski, Biol. 1010

27. Diffusion across a membrane Semipermeable membrane
The Plasma Membrane
2/16/2019
Osmosis
Diffusion across a membrane
Diffusion of water across a membrane
Moves from HIGH water potential (low solute) to LOW water potential (high solute)
Semipermeable membrane
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G. Podgorski, Biol. 1010

28. Diffusion of H2O Across A Membrane
The Plasma Membrane
2/16/2019
Diffusion of H2O Across A Membrane
High H2O potential Low solute concentration
Low H2O potential High solute concentration
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G. Podgorski, Biol. 1010

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The Plasma Membrane
2/16/2019
Aquaporins
Water Channels
Protein pores used during OSMOSIS
WATER MOLECULES
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G. Podgorski, Biol. 1010

30. Cell in Isotonic Solution
The Plasma Membrane
2/16/2019
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 _______________.
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G. Podgorski, Biol. 1010

31. Cell in Hypotonic Solution
The Plasma Membrane
2/16/2019
Cell in Hypotonic Solution
10% NaCL 90% H2O
CELL
20% NaCL
80% H2O
What is the direction of water movement?
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G. Podgorski, Biol. 1010

32. Cell in Hypertonic Solution
The Plasma Membrane
2/16/2019
Cell in Hypertonic Solution
15% NaCL 85% H2O
ENVIRONMENT
CELL
5% NaCL
95% H2O
What is the direction of water movement?
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G. Podgorski, Biol. 1010

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The Plasma Membrane
2/16/2019
Cells in Solutions
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G. Podgorski, Biol. 1010

34. NO NET MOVEMENT OF H2O (equal amounts entering & leaving)
The Plasma Membrane
2/16/2019
Isotonic Solution
Hypotonic Solution
Hypertonic Solution
NO NET MOVEMENT OF H2O (equal amounts entering & leaving)
CYTOLYSIS
PLASMOLYSIS
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G. Podgorski, Biol. 1010

35. Cytolysis & Plasmolysis
The Plasma Membrane
2/16/2019
Cytolysis & Plasmolysis
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Cytolysis
Plasmolysis
G. Podgorski, Biol. 1010

36. Osmosis in Red Blood Cells
The Plasma Membrane
2/16/2019
Osmosis in Red Blood Cells
Isotonic
Hypertonic
Hypotonic
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G. Podgorski, Biol. 1010

37. What Happens to Blood Cells?
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The Plasma Membrane
2/16/2019
isotonic
hypotonic
hypertonic
hypertonic
isotonic
hypotonic
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G. Podgorski, Biol. 1010

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40. Thursday September 17, 2015 Bell Ringer
Copy and answer the following:
If a blood cell were to be placed in an isotonic solution, what would happen to the size of the cell?
What would happen to the size of a cell if it were placed into a hypertonic solution?

41. Friday September 18, 2015 Bell Ringer
The Plasma Membrane
2/16/2019
Friday September 18, 2015 Bell Ringer
Answer the following questions:
What do you think is happening in the picture?
Do you think that the cell is using energy in the drawing?
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G. Podgorski, Biol. 1010

42. Three Forms of Transport Across the Membrane
The Plasma Membrane
Three Forms of Transport Across the Membrane
2/16/2019
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G. Podgorski, Biol. 1010

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The Plasma Membrane
2/16/2019
Passive Transport
Simple Diffusion
Doesn’t require energy
Moves high to low concentration
Example: Oxygen or water diffusing into a cell and carbon dioxide diffusing out.
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G. Podgorski, Biol. 1010

44. Facilitated diffusion
The Plasma Membrane
2/16/2019
Passive Transport
Facilitated diffusion
Doesn’t require energy
Uses transport proteins to move high to low concentration
Examples: Glucose or amino acids moving from blood into a cell.
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G. Podgorski, Biol. 1010

45. Proteins Are Critical to Membrane Function
The Plasma Membrane
2/16/2019
Proteins Are Critical to Membrane Function
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G. Podgorski, Biol. 1010

46. Types of Transport Proteins
The Plasma Membrane
2/16/2019
Types of Transport Proteins
Channel proteins are embedded in the cell membrane & have a pore for materials to cross
Carrier proteins can change shape to move material from one side of the membrane to the other
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G. Podgorski, Biol. 1010

47. Facilitated Diffusion
The Plasma Membrane
2/16/2019
Facilitated Diffusion
Molecules will randomly move through the pores in Channel Proteins.
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G. Podgorski, Biol. 1010

48. Facilitated Diffusion
The Plasma Membrane
2/16/2019
Facilitated Diffusion
Some Carrier proteins do not extend through the membrane.
They bond and drag molecules through the lipid bilayer and release them on the opposite side.
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G. Podgorski, Biol. 1010

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The Plasma Membrane
2/16/2019
Carrier Proteins
Other carrier proteins change shape to move materials across the cell membrane
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G. Podgorski, Biol. 1010

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The Plasma Membrane
2/16/2019
Active Transport
Requires energy or ATP
Moves materials from LOW to HIGH concentration
AGAINST concentration gradient
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G. Podgorski, Biol. 1010

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The Plasma Membrane
2/16/2019
Active transport
Examples: Pumping Na+ (sodium ions) out and K+ (potassium ions) in against strong concentration gradients.
Called Na+-K+ Pump
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G. Podgorski, Biol. 1010

52. Sodium-Potassium Pump
The Plasma Membrane
2/16/2019
Sodium-Potassium Pump
3 Na+ pumped in for every 2 K+ pumped out; creates a membrane potential
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G. Podgorski, Biol. 1010

53. Moving the “Big Stuff” Exocytosis- moving things out.
The Plasma Membrane
Moving the “Big Stuff”
2/16/2019
Exocytosis- moving things out.
Molecules are moved out of the cell by vesicles that fuse with the plasma membrane.
This is how many hormones are secreted and how nerve cells communicate with one another.
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G. Podgorski, Biol. 1010

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The Plasma Membrane
Exocytosis
2/16/2019
Exocytic vesicle immediately after fusion with plasma membrane.
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G. Podgorski, Biol. 1010

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The Plasma Membrane
Moving the “Big Stuff”
2/16/2019
Large molecules move materials into the cell by one of three forms of endocytosis.
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G. Podgorski, Biol. 1010

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The Plasma Membrane
Pinocytosis
2/16/2019
Most common form of endocytosis.
Takes in dissolved molecules as a vesicle.
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G. Podgorski, Biol. 1010

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The Plasma Membrane
2/16/2019
Pinocytosis
Cell forms an invagination
Materials dissolve in water to be brought into cell
Called “Cell Drinking”
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G. Podgorski, Biol. 1010

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The Plasma Membrane
Example of Pinocytosis
2/16/2019
mature transport vesicle
pinocytic vesicles forming
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Transport across a capillary cell (blue).
G. Podgorski, Biol. 1010

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The Plasma Membrane
2/16/2019
Receptor-Mediated Endocytosis
Some integral proteins have receptors on their surface to recognize & take in hormones, cholesterol, etc.
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G. Podgorski, Biol. 1010

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The Plasma Membrane
Receptor-Mediated Endocytosis
2/16/2019
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G. Podgorski, Biol. 1010

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The Plasma Membrane
2/16/2019
Endocytosis – Phagocytosis
Used to engulf large particles such as food, bacteria, etc. into vesicles
Called “Cell Eating”
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G. Podgorski, Biol. 1010

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The Plasma Membrane
Phagocytosis About to Occur
2/16/2019
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G. Podgorski, Biol. 1010

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The Plasma Membrane
2/16/2019
Phagocytosis - Capture of a Yeast Cell (yellow) by Membrane Extensions of an Immune System Cell (blue)
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G. Podgorski, Biol. 1010

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The Plasma Membrane
2/16/2019
Exocytosis The opposite of endocytosis is exocytosis. Large molecules that are manufactured in the cell are released through the cell membrane.
Inside Cell
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Cell environment
G. Podgorski, Biol. 1010

67. Thursday February 9, 2017 Bell Ringer
Answer the following question:
The experimental setup shows an osmometer. An osmometer is a device used to measure the amount of osmotic pressure exerted by a liquid passing through a semipermeable membrane. The graph shows one lab group’s results compared with the results of the rest of the class combined. Line A represents the results of the single lab group. Line B represents the data of the rest of the class.
Predict Look at the graph in Figure 7–12. How would the results differ if a sucrose solution with twice the concentration of the one used to collect the results represented by line A were used?
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