3.4 Diffusion and Osmosis KEY CONCEPT Materials move across membranes because of concentration differences.

3.4 Diffusion and Osmosis Passive transport does not require energy input from a cell. Molecules can move across the cell membrane through passive transport. There are two types of passive transport. diffusion osmosis

3.4 Diffusion and Osmosis Diffusion and osmosis are types of passive transport. Molecules diffuse down a concentration gradient.

3.4 Diffusion and Osmosis Diffusion and osmosis are types of passive transport. Osmosis is the diffusion of water molecules across a semipermeable membrane.

3.4 Diffusion and Osmosis Diffusion and osmosis are types of passive transport. There are three types of solutions. isotonic hypertonic hypotonic

3.4 Diffusion and Osmosis Some molecules can only diffuse through transport proteins. Some molecules cannot easily diffuse across the cell membrane. Facilitated diffusion is diffusion through transport proteins.

If And 3.4 Diffusion and Osmosis molecules and ions are always jiggling and this internal movement causes them to randomly collide with one another millions of times each second. And the rebounds from the collisions propel them through a liquid or gas with the result of being a gradual and complete mixing.

What factors can affect the speed at which this diffusion occurs? 3.4 Diffusion and Osmosis THEN What factors can affect the speed at which this diffusion occurs?

Factors that affect diffusion speed 3.4 Diffusion and Osmosis Factors that affect diffusion speed 1. Size It takes more energy to move a large than a small one.

Factors that affect diffusion speed 3.4 Diffusion and Osmosis Factors that affect diffusion speed 2. Concentration Molecules move faster at higher temperatures.

Factors that affect diffusion speed: 3.4 Diffusion and Osmosis Factors that affect diffusion speed: 3. Temperature Solutes tend to dissolve “down” a concentration gradient.

Factors that affect diffusion speed 3.4 Diffusion and Osmosis Factors that affect diffusion speed 4. Charge Each ion or charged molecule contributes to the overall electrical charge of the solution + to –

Factors that affect diffusion speed 3.4 Diffusion and Osmosis Factors that affect diffusion speed 5. Pressure. It squeezes molecules together; the more crowded they are, the more they rebound.

3.4 Osmosis

Diffusion across a cell membrane LAB INTRODUCTION