Diffusion and Movement Across a Membrane http://library.thinkquest.org/C004535/media/cell_membrane.gif http://www.enchantedlearning.com/subjects/animals/cell/anatomy.GIF

Diffusion Diffusion is - the movement of particles from an area of high concentration to an area of low concentration. http://environmentsofcells.wikispaces.com/file/view/800px-Diffusion_en_svg.png/217225506/800px-Diffusion_en_svg.png

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

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

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. http://farm6.static.flickr.com/5168/5326987932_0a46ac8c35.jpg

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. http://www.midnightexcess.com/wp-content/uploads/2010/09/cup-of-tea.jpg

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

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

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

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.

Active Transport This energy is called ATP

Active Transport Low Concentration High Concentration

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.

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

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

Venn Diagram Diffusion Active Transport