Presentation on theme: "Materials move across membranes because of concentration differences."— Presentation transcript:
1 Materials move across membranes because of concentration differences. 3.4 Diffusion and OsmosisMaterials move across membranes because of concentration differences.HighConcentrationLowConcentration
2 Molecules can move across the cell membrane through passive transport. 3.4 Diffusion and OsmosisMolecules can move across the cell membrane through passive transport.Passive transport does not require energy input from a cell.There are two types of passive transport:diffusionosmosis
3 DiffusionDiffusion- movement of molecules from a region of higher concentration to a region of lower concentration
4 Molecules diffuse down a concentration gradient 3.4 Diffusion and OsmosisConcentration gradient is the difference in the concentration of a substance from one location to anotherMolecules diffuse down a concentration gradient
5 3.4 Diffusion and OsmosisOsmosis is the diffusion of water molecules across a semipermeable membrane.
6 Osmosis There are three types of solutions. tonic = pressure 1) isotonic2) hypertonic3) hypotonic
7 3.4 Diffusion and OsmosisSome molecules can only diffuse through transport proteins and cannot easily diffuse across the cell membrane.Facilitated diffusion is diffusion through transport proteins.