1. Transport Across Cell Membrane
2.4

2. Passive Transport
the movement of materials across the cell membrane without the use of cell energy (ATP)
simple diffusion (including osmosis)
facilitated diffusion (using carrier proteins)

3. Simple Diffusion Image from: http://arditobook. pbworks
the movement of molecules from an area of higher concentration to an area of lower concentration
CO2, O2, H2O

4. Osmosis the diffusion of water across a selectively permeable membrane
water follows concentration gradient until equilibrium

5. Osmosis
movement of water into and out of cells is important in life processes
direction changes depending on type of solution:
isotonic solution
hypotonic solution
hypertonic solution

6. Cell in Isotonic Solution
The Plasma Membrane
4/25/2017
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 _______________.
copyright cmassengale 6
G. Podgorski, Biol. 1010 6

7. Cell in Hypotonic Solution
The Plasma Membrane
4/25/2017
Cell in Hypotonic Solution
10% NaCL 90% H2O
CELL
20% NaCL
80% H2O
What is the direction of water movement?
copyright cmassengale 7
G. Podgorski, Biol. 1010 7

8. Cell in Hypertonic Solution
The Plasma Membrane
4/25/2017
Cell in Hypertonic Solution
15% NaCL 85% H2O
ENVIRONMENT
CELL
5% NaCL
95% H2O
What is the direction of water movement?
copyright cmassengale 8
G. Podgorski, Biol. 1010 8

9. Cells and Tonicity Image from: http://chemistry. about

10. Red Blood Cells Image from: http://www. esu7

11. copyright cmassengale
The Plasma Membrane
4/25/2017
isotonic
hypotonic
hypertonic
hypertonic
isotonic
hypotonic
copyright cmassengale 11
G. Podgorski, Biol. 1010 11

12. How does this impact…
…a single-celled organism living in a freshwater environment?
…a single-celled organism living in a salt-water environment?
…the roots of a plant in the spring after salt has been sprinkled during the winter?

13. More applications… Why can’t you water a plant with salt water?
Why do vegetables in the grocery store get sprayed with water periodically? (What would happen if they were sprayed with salt water?)

14. Facilitated Diffusion Image from: http://schoolworkhelper
protein carrier molecules assist in diffusion of molecules across cell membrane
e.g. glucose into red blood cells

15. Active Transport Image from: http://thebasisoflife. wikispaces

16. Active Transport
the movement of materials against the concentration gradients
requires cellular energy (ATP)
primary & secondary active transport
important for reabsorption in kidneys, muscle contractions, nerve impulses, etc.

17. Active Transport often accomplished through protein channels
movement of larger substances through endocytosis and exocytosis

18. Endocytosis Image from: http://kentsimmons. uwinnipeg

19. Exocytosis Image from: http://library. thinkquest
Neurotransmitters

20. Credits
Slides #12, 13, 14, and 17 taken from Powerpoint presentations created by Cheryl Massengale, educator extraordinaire & creator of

21. Homework #1
Your biology study partner asks you a question about the concentration gradient of water. What is meant by the term “concentration gradient”? Is your study partner using the term correctly in reference to water? Explain why or why not.

22. Homework #2-3 Facilitated diffusion is specific. What does this mean?
A red blood cell was placed in a beaker of solution. The cell immediately began to swell and finally burst. Explain what happened, referring to the cytosol of the cell and the solution in the beaker.

23. Homework #4,5
Distilled water is considered hypotonic to body cells. Explain.
Compare the energy requirements of passive transport, primary active transport, and secondary active transport.

24. Homework #7
How does the concentration of a solute on the two sides of a membrane affect passive transport? How does this concentration affect primary and secondary active transport?