2Semipermeable Membrane The Cell Membrane is a Semipermeable membrane – it keeps some things out and lets some things in.Protects contentsof cell from outsideworld.Proteins are thebouncers
3What Materials can Pass? What can come into the cell?Oxygen & food & proteinsWhat goes out of the cell?Waste materialsWhat is not allowed in?Poison and waste
4PASSIVE TRANSPORTPASSIVE TRANSPORT – ways to move material into and out of the cell without using any energy.2 Ways:DIFFUSIONOSMOSIS – a type of diffusion
5DIFFUSIONThe main method by which small molecules move across the cell membrane.The molecules move from an area of HIGHER CONCENTRATION to an area of LOWER CONCENTRATION.Oxygen molecules commonly move into and out of the cell by Diffusion.USES NO ENERGY (passive transport)
8What Causes Diffusion?Molecules are always moving and they bump into each other.When they bump into each other they push each other away and spread out.Eventually they spread throughout the whole area.NO ENERGY NEEDED by cell because the molecules have energy in their vibrations.
9OSMOSIS A special kind of diffusion The diffusion of water molecules through the cell membrane.Water still moves from HIGHER CONCENTRATION to LOWER CONCENTRATION.USES NO ENERGY (passive transport)
13POTATO FISH!!!!Take out a sheet of paper!Write down observations of both of your potato slices.Put your name on both cupsLabel one cup SALT and one cup FRESHPut the same amount of water in each cupPut salt in the cup that is labeled salt (amount does not matter, just make sure it dissolves!)Put one potato slice in the FRESH cup and one in the SALT cupWe are going to leave the potatoes in their cups over night.Write down your predictions. WHAT DO YOU THINK WILL HAPPEN TO EACH OF THE POTATOES?
14ACTIVE TRANSPORTActive Transport – USES ENERGY to move materials into and out of the cell.Often from LOW concentration to HIGH concentrationFor small or large particlesThis requires the cell to USE ENERGY.2 ways:ENDOCYTOSISEXOCYTOSIS
15ENDOCYTOSIS USES ENERGY (active transport) Large particles are taken INTO THE CELLParticles include PROTEIN and FOOD
16ENDOCYTOSIS – draw these steps energyenergyA WANTEDMOLECULESTEP 1:The cell membranetouches the wantedmolecule.1
17ENDOCYTOSIS energy energy STEP 2: The cell wraps itself around the molecule.2
18ENDOCYTOSISenergySTEP 3:The moleculeforms a Vacuole.3
20TRANSPORT PROTEINSThese are special Proteins called Transport Proteins that are attached to the cell membrane.They “PICK UP” the wanted molecules inside or outside of the cell and carry them in or out using energy.Common Materials transported this way:Calcium, Potassium, and Sodium.
21TRANSPORT PROTEINS CYTOPLASM OUTSIDE THE CELL HIGH LOW TRANSPORT CONCENTRATION CONCENTRATIONTRANSPORTPROTEINBEFORE
22TRANSPORT PROTEINS CYTOPLASM OUTSIDE THE CELL HIGH LOW USES ENERGY CONCENTRATION CONCENTRATIONUSES ENERGYAFTER