October 8, 2013 Warm Up: What is an e-? Homework: Prepare for the vocabulary quiz and begin to work on the study guide for the Prokaryote and Eukaryote Cell Test Scheduled for Wednesday October 16, 2013 Class Work: Take Cornell Notes from the Diffusion and Osmosis Power Point.

Diffusion & Osmosis

Cell Membrane Outer membrane of cell that controls movement in and out of the cell Double layer http://library.thinkquest.org/12413/structures.html

Define Diffusion The movement of molecules from a area in which they are highly concentrated to a area in which they are less concentrated.

Draw a diagram of an example of diffusion we saw in class.

Define osmosis The diffusion of water across a selectively permeable membrane.

Define osmosis   Water moves from a high concentration of water (less salt or sugar dissolved in it) to a low concentration of water (more salt or sugar dissolved in it).  This means that water would cross a selectively permeable membrane from a dilute solution (less dissolved in it) to a concentrated solution (more dissolved in it). http://www.usd.edu/~bgoodman/Osmos.htm

Define osmosis http://www.usd.edu/~bgoodman/Osmos.htm

Define osmosis In this picture a red blood cell is put in a glass of distilled water (all water with no salt or sugar in it).  Because there is a higher concentration of water outside the cell, water enters the cell by OSMOSIS.  In this case too much water enters and the cell swells to the point of bursting open.  In the end pieces of cell membrane are left in the water. http://www.usd.edu/~bgoodman/Osmos.htm

Define selectively permeable membrane A membrane that allows only certain materials to cross it Materials pass through pores in the membrane

Why are osmosis & diffusion important? All living things have certain requirements they must satisfy in order to remain alive – maintain homeostasis These include exchanging gases (usually CO2 and O2), taking in water, minerals, and food, and eliminating wastes. These tasks happen at the cellular level. Molecules move through the cell membrane by diffusion

Why are osmosis & diffusion important? All living things have certain requirements they must satisfy in order to remain alive. These include exchanging gases (usually CO2 and O2), taking in water, minerals, and food, and eliminating wastes. These tasks ultimately occur at the cellular level, and require that molecules move through the membrane that surrounds the cell.

Why are osmosis & diffusion important? This membrane is a complex structure that is responsible for separating the contents of the cell from its surroundings, for controlling the movement of materials into and out of the cell, and for interacting with the environment surrounding the cell. Video

PASSIVE TRANSPORT - TAKING THE EASY ROAD Passive transport does not require energy for a substance to move across the plasma membrane. Osmosis is an example of passive transport Gradient: high concentration to low concentration

ACTIVE TRANSPORT - ENERGY TO TRANSPORT Active transport describes what happens when a cell uses energy to transport something

Osmosis Lab virtual Cell Membrane and Passive and Active Transport Lab Bench Diffusion and Osmosis