1. Topic: Cell Transport pg. 23
The Plasma Membrane
1/18/2019
Topic: Cell Transport pg. 23
EQ: Explain how molecules are transported across a semi-permeable membrane.
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G. Podgorski, Biol. 1010

2. copyright cmassengale
The Plasma Membrane
1/18/2019
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

3. copyright cmassengale
The Plasma Membrane
1/18/2019
Diffusion of Liquids
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G. Podgorski, Biol. 1010

4. Diffusion through a Membrane
The Plasma Membrane
1/18/2019
Diffusion through a Membrane
Cell membrane
Solute moves DOWN concentration gradient (HIGH to LOW)
G. Podgorski, Biol. 1010

5. copyright cmassengale
The Plasma Membrane
1/18/2019
Osmosis
Diffusion of water across a membrane
Moves from HIGH water potential (low solute) to LOW water potential (high solute)
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G. Podgorski, Biol. 1010

6. Diffusion of H2O Across A Membrane
The Plasma Membrane
1/18/2019
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

7. Facilitated diffusion
The Plasma Membrane
1/18/2019
Passive Transport
Facilitated diffusion
No energy required
Uses transport proteins to move high to low concentration
Examples: Glucose or amino acids moving from blood into a cell.
Draw this
copyright cmassengale
G. Podgorski, Biol. 1010

8. Proteins Are Critical to Membrane Function
The Plasma Membrane
1/18/2019
Proteins Are Critical to Membrane Function
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G. Podgorski, Biol. 1010

9. Types of Transport Proteins
The Plasma Membrane
1/18/2019
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
copyright cmassengale
G. Podgorski, Biol. 1010

10. Facilitated Diffusion
The Plasma Membrane
1/18/2019
Facilitated Diffusion
Molecules will randomly move through the pores in Channel Proteins.
copyright cmassengale
G. Podgorski, Biol. 1010

11. Facilitated Diffusion
The Plasma Membrane
1/18/2019
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.
copyright cmassengale
G. Podgorski, Biol. 1010

12. copyright cmassengale
The Plasma Membrane
1/18/2019
Carrier Proteins
Other carrier proteins change shape to move materials across the cell membrane
copyright cmassengale
G. Podgorski, Biol. 1010

13. copyright cmassengale
The Plasma Membrane
1/18/2019
Active Transport
Requires energy or ATP
Moves materials from LOW to HIGH concentration
AGAINST concentration gradient
Draw this
copyright cmassengale
G. Podgorski, Biol. 1010

14. copyright cmassengale
The Plasma Membrane
1/18/2019
Active transport
Examples: Pumping Na+ (sodium ions) out and K+ (potassium ions) in against strong concentration gradients.
Called Sodium-Potassium Pump
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G. Podgorski, Biol. 1010

15. Sodium-Potassium Pump
The Plasma Membrane
1/18/2019
Sodium-Potassium Pump
3 Na+ pumped in for every 2 K+ pumped out; creates a membrane potential
copyright cmassengale
G. Podgorski, Biol. 1010

16. Exocytosis- moving things out.
The Plasma Membrane
Moving the “Big Stuff”
1/18/2019
Exocytosis- moving things out.
Molecules are moved out of the cell by vesicles that fuse with the plasma membrane.
G. Podgorski, Biol. 1010

17. copyright cmassengale
The Plasma Membrane
1/18/2019
Endocytosis
Used to engulf large particles such as food, bacteria, etc. into vesicles
Called “Cell Eating”
copyright cmassengale
G. Podgorski, Biol. 1010