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Cellular Transport Biology 11 Cell Membrane Selectively permeable Allows some molecules to pass through while stopping others Continually allows water, gases, nutrients and wastes to pass What if the cell membrane was … ? Permeable Allowing all molecules to pass through Impermeable Allowing no molecules to pass through Particle Theory Molecules constantly move in all directions Bounce off of one another when they collide Result: Molecules concentrated in one area spread outward Terms to Know Solute Solvent Solid substance E.g. sugar Fluid E.g. water Solution Solute + solvent mixed together Concentration Gradient Concentration of solutes is unequal on either side of the membrane Outside and inside of cell Unequal distribution Dynamic Equilibrium A balance is reached and maintained Molecules continue to cross membrane Rate of molecules entering cell will equal that of them leaving Passive Transport Movement of materials across a cell membrane without expending energy Molecules move from high to low concentration With the concentration gradient Until dynamic equilibrium is reached Types of Passive Transport 1. Diffusion 2. Osmosis 3. Facilitated Diffusion Flowing downhill Passive Transport – Diffusion When there is an unequal concentration of gas or liquid molecules Passive Transport – Osmosis Diffusion of water Membrane is permeable to water, but impermeable to larger molecules Cell may gain or lose water Osmosis – Water Movement A solution that has the same concentration of solutes as the cell. Therefore there is no net movement of water molecules Hypertonic The solution has higher concentration of solutes then the cell. Therefore there will be a net movement OUT of the cell. Hypotonic A solution that has a lower concentration of solutes than the cell. There will be a net movement of water into the cell. Passive Transport – Facilitated Diffusion When integral/carrier proteins in the cell membrane aid diffusion Materials move in and out of the cell much more quickly than regular diffusion Passive Transport – Facilitated Diffusion Passive Transport – Diagrams Active Transport Materials move from area of low to high concentration Requires energy Against the concentration gradient Makes concentration gradient more unequal ATP – adenosine triphosphate Integral/carrier proteins may be used Active Transport – Diagram Other Types of Active Transport 1. 2. Endocytosis a. Pinocytosis b. Phagocytosis Pushing something uphill Exocytosis No proteins used with these! Animation Active Transport – Endocytosis Movement of large particles into the cell Extends cytoplasm around it to engulf (completely surround) the particle Types of Endocytosis Phagocytosis Pinocytosis Liquid droplets are engulfed Large molecules, or even whole cells, are engulfed Solids Active Transport Active Transport – Exocytosis Movement of large particles out of the cell Vesicles fuse to cell membrane Dump interior of vesicle outside of cell Often eliminates wastes Active Transport – Exocytosis Active Transport – Diagrams Task Read: Pages 50-53 & 56-57 Summary: pages 57-58 Answer: Practice Questions: #1, 2a, 3 – 6 (pg 57) #1 – Affects Diffusion Rates: Concentration Pressure Difference between inside and outside of cell Larger difference = faster High pressure = faster Temperature Which is faster? High temperature Did you know? Average cell is 20–30 µm 3 seconds for oxygen to enter @ room temperature If it was 20 cm … it would take 11 years! #2(a) - Solutions Isotonic Hypotonic Concentration of solutes outside cell is equal to that inside Concentration of solutes outside cell is less than inside Hypertonic Concentration of solutes outside cell is greater than inside #3 – Diffusion Compared Facilitated Diffusion Carrier/integral protein used Diffusion/Osmosis Proteins not used Quicker movement Movement through phospholipids Slower movement #4 – Passive vs. Active Transport Passive Active No energy used Energy used Movement WITH concentration gradient Movement AGAINST concentration gradient From high to low concentration (Flowing downhill) From low to high concentration (Pushing uphill) #5 – Endocytosis Pinocytosis Phagocytosis Intakes or engulfs small liquid droplets E.g. water and fats Intakes or engulfs solid particles Both use energy! #6 – Endo vs. Exocytosis Endocytosis Molecules entering cell Exocytosis Molecules exiting cell (removed) Cytoplasm extended around molecule Both use energy Move to external environment Fuses with cytoplasm Extra Questions 1. How are osmosis and diffusion alike? How are they different? 2. Someone sprayed perfume at the front of the classroom. You smell it at the back of the room a short time later. Explain what has occurred. Task: Complete Review Chart Passive Transport Diffusion Requires energy Requires integral proteins Moves from ? to ?concentration Movement across concentration gradient Moves what materials Osmosis Facilitated Diffusion Active Transport Task: Complete Review Chart Passive Transport Diffusion Requires energy Requires integral proteins Moves from ? to ?concentration Movement across concentration gradient Moves what materials Osmosis No Facilitated Diffusion Active Transport Yes Task: Complete Review Chart Passive Transport Diffusion Requires energy Requires integral proteins Moves from ? to ?concentration Movement across concentration gradient Moves what materials Osmosis Facilitated Diffusion No No No Active Transport Yes Yes Usually Task: Complete Review Chart Passive Transport Diffusion Requires energy Requires integral proteins Moves from ? to ?concentration Movement across concentration gradient Moves what materials Osmosis Facilitated Diffusion No No No High to Low Active Transport Yes Yes Usually Low to High Task: Complete Review Chart Passive Transport Diffusion Requires energy Requires integral proteins Osmosis Facilitated Diffusion No No No Active Transport Yes Yes Usually Moves from ? to ?concentration High to Low Low to High Movement across concentration gradient With Against Moves what materials Task: Complete Review Chart Passive Transport Diffusion Requires energy Requires integral proteins Osmosis Facilitated Diffusion No No No Active Transport Yes Yes Usually Moves from ? to ?concentration High to Low Low to High Movement across concentration gradient With Against Moves what materials Liquids & Gases Water Solids (& gas) Solids What is the end result? Passive transport Reaches dynamic equilibrium Active transport Makes molecules more unequal Videos Aliant Learning Cell Movement and Transport 2001 - 15 min http://www.youtube.com/watch?v=GW0lqf4Fqpg http://www.youtube.com/watch?v=JShwXBWGM yY MacGraw Hill Animations http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapte r2/