What you'll Learn:
You will discover how molecules move across the plasma membrane and how they move from place to place in a fluid (like inside a cell).

Why its important:
Transportation of substances through the plasma membrane is important to maintain homeostasis in your cells and keep an organism healthy.
An understanding of diffusion is vital to understanding how and why things happen in your environment.

We divide Diffusion and Osmosis and Cellular Transport into two different sections in our classroom, but they are directly related. Scroll to the bottom of the page to find the section on Cellular Transport.



Here is the power point we used in class. Let me know if the links don't work.




Here is a vocabulary sheet for you to sort out all your new vocabulary words.
Suggested words are:
1. Adhesion
2. Cohesion
3. Polar
4. Non Polar
5. Hydrogen Bond
6. Covalent Bond
7.Passive Transport (diffusion and osmosis)
ADDED Semipermeable
8.Concentration Gradient
9. Kinetic Energy
10. Brownian motion
11. Dynamic Equilibrium


When you are done studying your vocabulary, try this study guide.


Online Activities for Diffusion and Osmosis

Today we will look at several different examples of the properties of water, and examples of diffusion and osmosis.

Here's what I expect you to learn from the web activity...

Overview and Learning Objectives

Materials such as water, nutrients, dissolved gases, ions and waste are constantly moving across a cell's membrane. In this activity, you will interact with models of diffusion and osmosis and observe the flow of molecules in air, in cells, and across a cell's semi-permeable membrane.

You and your partner will be able to:
  • determine that diffusion results from random motion and/or collisions of particles;
  • learn that particles diffuse from high concentration to low concentration;
  • explore simple diffusion across a semi-permeable membrane.
  • connect the process to dialysis.


1. To run the program for the activity, you will click on the "Go to Activity" link on the website linked below. The link is below the picture. A warning will pop up, saying the digital signature cannot be verified, just click on run, the site has been checked out, and it is fine.


2. Once the program starts you will begin by clicking "Concentration"

Remember, read each page carefully, I am not there to help you, so you are "on your own".

3. At the end of the activity, print your report WITHOUT registering to our library and turn it in. If you don't do this step you will have to repeat the entire lab on your own time.
4. Once you have completed and printed the first activity, continue to the second, below.
Did you read all of the four steps above? If you didn't, go back and make sure you understand what to do before you start. The rest of the directions will be given in the activity, so read it carefully.

Diffusion and Osmosis Activity


Part II (more difficult)

Once you have completed this activity, you should continue your study of how cells are affected by diffusion and osmosis with the activity Diffusion, Osmosis and Active Transport. This activity is more difficult, but it addresses many of the same concepts as the previous one, and also requires you to print a report. The first part is an extension of the first activity, presented in a slightly different way. The second part helps you to see how a cell can control what enters or exits it.

Overview and Learning Objectives

You will investigate diffusion, osmosis and study the role of surface area in facilitating diffusion. You will apply what you have learned to a blood cell traveling through different concentrations of oxygen. Then, you will explore a 3D aquapore embedded in a membrane. Using the Molecular Rover, you can fly through the aquapore, and consider how it facilitated your travel from one side of the membrane to another.

When you are done, you should be able to:
• Compare diffusion and osmosis.
• Explain how concentration differences affect the overall flow of molecules.
• Contrast molecular movement of materials in and out of equilibrium and describe the dynamic nature of equilibrium.
• Apply the principles of diffusion to red blood cells in a real biological system.
• Explain how increased surface area increases the rate of diffusion.

1. To run the program for the activity, you will click on the "Go to Activity" link on the website linked below. The link is below the picture. A warning will pop up, saying the digital signature cannot be verified, just click on run, the site has been checked out, and it is fine.


2. Once the program starts you will begin by clicking "Concentration"

Remember, read each page carefully, I am not there to help you, so you are "on your own".

3. At the end of the activity, print your report WITHOUT registering to our library and turn it in. If you don't do this step you will have to repeat the entire lab on your own time.
Did you read all of the three steps above? If you didn't, go back and make sure you understand what to do before you start. The rest of the directions will be given in the activity, so read it carefully.


Diffusion, Osmosis and Active transport


Final Report
Directions: After completing the unit, answer the following questions to review.
  1. During diffusion molecules move from areas of high concentration to areas of low concentration. Is this process spontaneous or directed by the cell? Explain.
  2. Red blood cells (with the help of hemoglobin) pick up oxygen in the lungs and drop it off to the rest of the body tissues. Explain how this is an example of diffusion in action.
  3. Give an example of a molecule that can move easily through a cell membrane. Give an example of a molecule that requires assistance to cross the cell membrane. Why are there differences in how molecules can cross the cell membrane?
  4. Diffusion and osmosis refer to the movement of particles until they reach equilibrium. What is active transport? Why is this process sometimes necessary for cells?




Cellular Transport - Beyond Osmosis and Diffusion

Although we studied most of this earlier in the year, we must also talk about Cellular Transport, which includes:


Osmosis
Diffusion
Facilitated Diffusion
Active Transport
Endocytosis
Exocytosis


• Cellular Transport Outline
1. Complete the vocabulary at the beginning of the section
2. Write each blue or red heading and take notes about each
3. Make sure you have completed questions 1-5 on page 206
4. Sketch (or describe) each illustration in the text
5. Write questions you think would be on the test