Presentation on theme: "Moving Substances Across Cell Membrane"— Presentation transcript:
1 Moving Substances Across Cell Membrane cell membrane is semi–permeableSome molecules pass through easily, some need helpSome molecules pass through without the expenditure of energy (spontaneous) and some require an input of energy (ATP)What molecules move IN and OUT of a cell:Small nonpolar molecules (CO2, O2)Small polar molecules such as waterIons and charged moleculesLarge polar molecules (eg. Glucose)MacromoleculesMovement IN and OUT canBe PASSIVE or ACTIVE
2 Passive Transport [High][Low] cell uses no energy molecules move randomlyMolecules spread out from an area of high concentration to an area of low concentration.[High][Low]Three types:DiffusionFacilitative DiffusionOsmosishighlowWeeee!!!
3 Simple Diffusion Animation Passive Transport:Diffusion: random movement of particles from an area of [high] to an area of [low].diffusion continues until all molecules are evenly spaced (equilibrium is reached)-Note: molecules will still move around but stay spread out.
4 Facilitated diffusion (Channel Protein) Diffusion (Lipid Bilayer) Passive Transport:AB2. Facilitated diffusion: diffusion of particles from [H L] through transport proteins found in the membraneTransport Proteins arespecific – they “select” onlycertain molecules to crossthe membraneFacilitated diffusion (Channel Protein)Diffusion (Lipid Bilayer)Carrier Protein
5 Passive Transport:Osmosis animation3.Osmosis: diffusion of water through a selectively permeable membrane from an area of [H L]Water moves freely through pores.Solute (green) too large to move across.
6 Effects of Osmosis on Life Water molecules are so small and so numerous that cells can’t control movement of water through the cell membrane.So what determines the direction of water movement?The environment around the cell,…specifically,the concentration of water molecules inside the cell compared to outsideEnvironment around the cell is either:HYPOTONIC, ISOTONIC, HYPERTONIC
7 But first - Don’t confuse Volume of water with Concentration Equal Volumes, Different Concentration
8 Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Hypotonic: The external environment (ECF) has a lower concentration of solutes and a higher concentration of water than inside the cell.Result: Water moves from the ECF to inside the cell- Cell Swells and bursts open (cytolysis)!
9 Compare a blood cell in an isotonic environment with one in a hypotonic environment
10 Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Isotonic SolutionIsotonic: The concentration of solutes in the ECF is equal to the concentration of solutes inside the cell.Result: Water moves equally in both directions and the cell remains same size. (Dynamic Equilibrium)
12 Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Hypertonic SolutionHypertonic: The ECF has a higher concentration of solutes and a lower concentration of water than inside the cell.shrinksResult: Water moves from inside the cell into the solution: Cell shrinks. Plasmolysis (plant cell) Crenation (animal cell)
13 B C A In what type of solution are these cells? Hypertonic Isotonic Plant cells resist bursting. Why?HypertonicIsotonicHypotonic
14 Active Transport cell uses energy Animations of Active Transport & Passive TransportActive Transportcell uses energyactively moves molecules to where they are neededMovement of molecules from an area of [low] to an area of [high]Three TypesProtein PumpsEndocytosisExocytosishighlowThis is gonna be hard work!!
15 Types of Active Transport Sodium Potassium Pumps (Active Transport using proteins)1. Protein Pumps –are special transport proteins that help move molecules IN/OUT - require energy to do workexample: Na+/K+ Potassium Pumps are important in nerve responses.Protein changes shape to move molecules: this requires energy!
16 Types of Active Transport 2. Endocytosis: taking bulky material into a cellUses energyCell membrane folds itself around food particle“cell eating”forms food vacuole & digests foodThis is how white blood cells eat bacteria!
17 Types of Active Transport 3. Exocytosis: Forces material out of cell in bulkmembrane surrounding the material fuses with cell membraneCell changes shape – requires energyEX: Hormones or wastes released from cellEndocytosis & Exocytosis animations