1. Diffusion and Movement Across a Membrane

2. Diffusion
Diffusion is - the movement of particles from an area of high concentration to an area of low concentration.

3. Diffusion
The diffusion of these molecules down the concentration gradient does not require energy

4. Diffusion
Diffusion stops when concentration on both sides of the cell membrane are equal.
Equilibrium or a balance is reached.

5. Diffusion A good example of diffusion is food coloring.
If you place a drop of red food coloring in a beaker of water eventually the entire beaker of water will have a red tint.

6. Diffusion Other everyday examples of diffusion are:
1.    Sugar will diffuse through tea until the entire cup of tea is sweet. (We stir the tea to speed up the diffusion.)
2.    The odor of food cooking diffuses throughout the kitchen. If you open the kitchen door it will spread into the next room.

7. Diffusion Examples of diffusion in science are:
1. Carbon dioxide leaving the mitochondria during cellular respiration
2. Oxygen entering the mitochondria during cellular respiration

8. Factor Affecting Diffusion Across a Plasma Membrane
The size of a molecule
Smaller molecules diffuse more quickly across the membrane
Some examples of small molecules include
Oxygen
CO2
Water

9. Active Transport
Active Transport is the movement of molecules from low to high concentration.

10. Active Transport
Naturally molecules from areas of high low concentrations, moving down the concentration gradient.
However, with active transport molecules are moving from low high, moving “up or against” the concentration gradient.
Therefore, ENERGY MUST be used.

11. Active Transport
This energy is called ATP

12. Active Transport
Low Concentration
High
Concentration

13. Diffusion vs Active Transport
1. Which cell, A or B, represents diffusion? Justify your response.
2. Which cell, A or B, represents active transport? Justify your response.

14. Diffusion vs. Active Transport
Directions: Respond to the questions in your notes using the diagram below.

15. Making a Comparison
Directions: Based on the information provided in this presentation, fill out the Venn diagram comparing and contrasting diffusion with active transport

16. Venn Diagram
Diffusion
Active Transport