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Active transport

Active transport






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    Active transport Active transport Presentation Transcript

    • Gateway to the Cell
    •  Thecell membrane is flexibleand allows a unicellularorganism to move
    •  Protective barrier Regulate transport in & out of cell (selectively permeable) Allow cell recognition Provide anchoring sites for filaments of cytoskeleton
    •  Provide a binding site for enzymes Interlocking surfaces bind cells together (junctions) Contains the cytoplasm (fluid in cell)
    • Phospholipids Proteins (Integral & Peripheral)Cholesterol Carbohydrates (glucose)
    •  Diffusion of water across a membrane Moves from HIGH water potential (low solute) to LOW water potential (high solute) Doesn’t require energy
    • Simple Diffusion Doesn’t require energy Moves high to lowconcentration Example: Oxygendiffusing into a cell andcarbon dioxide diffusingout
    •  Facilitated diffusion Doesn’t require energy Uses transport proteins to move high to low concentration Examples: Glucose or amino acids moving from blood into a cell.
    •  Channel proteins are embedded in the cell membrane & have a pore for materials to cross Carrier proteins can change shape to move material from one side of the membrane to the other
    •  Molecules will randomly move through the pores in Channel Proteins.
    •  Some Carrier proteins do not extend through the membrane. They bond and drag molecules through the lipid bilayer and release them on the opposite side.
    •  Other carrier proteins change shape to move materials across the cell membrane
    •  Requires energy or ATP Moves materials from LOW to HIGH concentration AGAINST concentration gradient
    •  Examples: Pumping Na+ (sodium ions) out and K+ (potassium ions) in against strong concentration gradients. Called Na+-K+ Pump
    • 3 Na+ pumped in for every 2 K+ pumpedout; creates a membrane potential
    • Endocytosis- moving things in.Cells absorb molecules by engulfing them.http://www.youtube .com/watch? v=4gLtk8Yc1Zc
    • Exocytosis-Exocytosis movingthings out. Molecules are moved out of the cell by vesicles that fuse with the plasma membrane. This is how many hormones are secreted and how nerve cells communicate with one another. another
    • Exocytic vesicleimmediately after fusionwith plasma membrane.