Osmosis Diffusion Intro - YouTube Diffusion/Osmosis Osmosis Diffusion Intro - YouTube

Diffusion: Movement of molecules across a cell membrane Diffusion requires NO ENERGY Molecules move from HIGH to LOW concentration. Let’s see! Let’s see MORE!

Facilitated Diffusion Many cell membranes have special channels (carrier proteins) that allow molecules to cross it. These channels help or facilitate diffusion to happen. This is known as facilitated diffusion. Like regular diffusion, will ONLY occur if there is a higher concentration of molecules on one side of the membrane. Let’s see!

Osmosis Osmosis: Movement of WATER from an area of more water (H) to an area of less water (L) Water moves OPPOSITE of all other molecules (i.e. solutes)!

How does osmosis work? Across a SEMI-PERMEABLE membrane Only certain molecules, like water, can move freely across the membrane Water molecules move from HIGH to LOW They want to BALANCE OUT a solution Therefore, water moves OPPOSITE of other molecules Let’s See!

salt moves out to balance Example of Osmosis #1 Condition #1: More Water outside of cell Inside cell = 98% Water, 2% salt Outside cell = 100% Water, 0% salt Water moves into cell, salt moves out to balance CELL SWELLS or BURSTS!

salt moves in to balance Example of Osmosis #2 Condition #2: More water inside of cell Inside cell: 98% Water, 2% Salt Outside cell: 95% Water, 5% Salt Water moves out of cell, salt moves in to balance CELL SHRIVELS!

Osmotic Pressure Cells behave differently when placed in different solutions! This is due to OSMOSIS! Most cells are ~ 98% water! Three types of osmotic pressure: Hypotonic Hypertonic Isotonic

Hypotonic Condition Cell is placed in 100% water Solution outside of cell has MORE water, less of other materials (i.e., salt) Therefore, solution is below strength (hypo) 100% Water ENTERS cell 98% CELL SWELLS!

Red Blood Cells in Hypotonic Solution - YouTube

Hypertonic Condition Cell is placed in 95% water Solution outside of cell has LESS water, more of other materials (i.e., salt) Therefore, solution is above strength (hyper) Water LEAVES cell 95% 98% CELL SHRINKS!

Red Blood Cells in a Hypertonic Solution - YouTube

Isotonic Condition Cell is placed in 98% water Solution outside of cell has SAME water, same amount of other materials (i.e., salt) Therefore, solution is equal strength (iso) Water moves equally; Equilibrium exists 98% CELL STAYS THE SAME! 98%

Red Blood Cells in an Isotonic Environment - YouTube

Review of Osmosis Isotonic, Hypertonic, Hypertonic Animation You Tube Onion Cell Osmosis

Active Transport Sometimes, materials will move across the cell membrane AGAINST a concentration gradient. LOW HIGH This is Active Transport. THIS REQUIRES ENERGY!!! Just like pulling something uphill! Cells get this energy from ATP (Adenosine Triphosphate)