How the Cell Membrane Works Click on the

How the Cell Membrane Works Click on the following link for a quick overview – Cellular Transport

Cell Membrane Structure What cell membranes look like under the microscope: EM Nuclear pore Normal Cell – EM Microscopic Click for movie and activity

Transport across a cell membrane Reasons for a cell membrane 1. Cells need an inside and an outside 2. Cell membrane separates the cell from its environment Can it be an impenetrable boundary? NO In Food Out Water Oxygen CO 2 Waste Cells need to let materials in and products or waste out How do they do this? ?

One way to get materials in and out of the cell is with Passive Transport There are 3 types of passive transport 1. Diffusion 2. Osmosis 3. Facilitated Diffusion What is Passive Transport ? Watch this Brain. Pop movie and see if you can find out. Brain. Pop – Passive Transport

Diffusion is the movement of molecules from a high concentration to a low concentration. hypertonic solution = "more solute, less water" hypotonic solution = "less solute, more water" isotonic solution = "equal solute and water" Picture of diffusion with one and two solutes Diffusion Demo Watch this and do it in the classroom A short video showing diffusion A short video explaining diffusion Movie and quiz

More on Diffusion Start this demo at the beginning of class What affects diffusion: Diffusion occurs with and/or without the 1. Temperature aid of a pore, or carrier protein 2. Size of molecule 3. Concentration gradient Brain. Pop Diffusion

Osmosis • Osmosis is a special type of diffusion. When water molecules are moving from a high concentration to an area of low concentration, it is called Osmosis. See the movie that shows this Short movie and quiz Demo of a Hypertonic and Hypotonic solution Interactive diffusion and osmosis Interactive cell in hypertonic and hypotonic solution

Facilitated Diffusion Click on image to see example of facilitated diffusion • Facilitated diffusion is similar to diffusion in that it take no energy from the cell. Some molecules are too large to move across the cell membrane and need help from carrier molecules or channel proteins. • Mc. Graw-Hill – Facilitated Diffusion • Passive and active transport press the review button to see the demo again. Then click on “Closer Look Facilitated Diffusion”. Close the window and press the practice button to check your understanding.

Transport Concepts Passive vs. Active Passive Active

Active Transport • Active transport requires energy (ATP) • Cells use Active transport when they must move materials against a concentration gradient. • Click on the picture below. On the web page click on the review button to see how active transport works. Notice that there is a high concentration of solute outside the cell and at the end there is a high concentration of solute inside the cell. • Test for understanding by clicking on Test

Active Transport • Watch Brain. Pop – Active Transport