1. CH 8: Cellular Transport

2. Diffusion and Osmosis What is diffusion?
- the movement of molecules from regions of high concentration to regions of low concentration, “down” a concentration gradient.
What is osmosis?
The diffusion of water across a selectively permeable membrane
Why do we need to regulate osmosis?
To maintain homeostasis because the plasma membrane is naturally permeable to water

4. Osmosis
How long does water diffuse in a solution? Until it has reached equilibrium (even distribution)
What controls osmosis?
The concentration gradient
What is a concentration gradient?
The unequal distribution of particles

5. Types of Solutions: Isotonic Remember: Salt Sucks!!!
"ISO" means the same
Definition: When the concentration of water is the same inside and outside the cell so a cell remains the same.
Both animal and plant cells retain normal shape and pressure

6. Types of Solutions: Hypotonic
The prefix "HYPO" means less
-Less water inside the cell than outside so water will move into the cell.
Definition: When the concentration of water is lower inside the cell than outside the cell so the cell swells
What happens: The cell swells up
Animal Cell- swell until they burst
Plant Cell- swell beyond their normal size as pressure increases; this pressure is called turgor pressure. The plasma membrane presses against the cell wall and makes the cell more firm (why grocers mist fruits at the market)

7. Types of Solution: Hypotonic

8. Types of Solution: Hypertonic
The prefix "HYPER" means more
-More water inside the cell than outside so the water leaves the cell.
Definition: When the concentration of water is higher inside the cell than outside the cell so the cell shrivels
What happens: Cell shrivels up
Animal cell- shrivels up
Plant cell – loses pressure as the plasma membrane shrinks away from the cell wall; the plant wilts = plasmolysis

9. Types of Solution http://www. tvdsb. on

10. Red Blood Cells in Solution
Burst Swollen Normal Plasmolysis

13. Passive Transport: No Energy Required
Passive Transport -the movement of particles across a membrane that goes with the concentration gradient…high concentration low concentration…and energy is not required
What do materials need to cross the plasma membrane? Transport proteins
What is this process called?
Facilitated diffusion

14. Types of Transport Proteins
Channel Proteins- form channels that allow specific molecules to flow through.
Carrier Proteins - change shape to allow a substance to pass through the plasma membrane.

15. Active Transport: Requires Energy
Active Transport – Movement of particles through a membrane against a concentration gradient…low concentration high concentration…Energy is required
How does active transport occur?
A carrier protein binds with the substance to be transported. The protein changes shape so that the particle can be released into the cell--like the opening of a door.

16. Type of
Transport
Protein Used?
Direction of
Movement
Requires
energy from
the cell?
Classification
of transport
Simple
Diffusion No
With
Concentration
Gradient
Passive
Facilitated
Yes- channel protein or carrier protein
Active
Yes- carrier protein
Against
Yes

17. Passive Transport vs. Active Transport

18. Transport of Large Particles
Endocytosis- The process by which a cell surrounds and takes in material from its environment
Explain the process of endocytosis- the material is engulfed and enclosed by a portion of the cells plasma membrane.

19. Exocytosis
Exocytosis- the expels or secretes materials from a cell.

20. Transport of Large Particles
Phagocytosis- the engulfing and ingesting of solid particles- “cell eating”
Pinocytosis- the ingestion of fluid into a cell- “cell drinking”