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Transport Across the Membrane (Summary of Protein Mediated Transport) SEC 4.2, 4.4 4.5, PAGES 72- 79 Transport can be PASSIVE or ACTIVE PASSIVE With Concentration Gradient, No ATP needed, like “rolling down a hill Diffusion Facilitated Channel Proteins or Carrier Proteins ACTIVE Against Concentration Gradient, Requires ATP With Proteins “Pumps” With Vesicles Exo and Endocytosis A. Transport by Carrier Proteins Sec 4.4 Specific proteins that combine with specific molecules • Carrier changes shape upon when combines then returns to initial shape • Involved in both Passive (Facilitated) Transport & Active too! B. Transport by Vesicles Sec 4.5 EXOCYTOSIS export OUT of cell ENDOCYTOSIS INTO cell 3 types P- Passive? A- Active? PASSIVE PASSIVE Name of Process Direction Requirements Examples? Diffusion High Conc. Gradient concentration to Only Low Gases- O2 Small Lipid soluble Water (osmosis) Facilitated Transport High Conc. To Low Conc. Gradient & Channel or Carrier Protein Some sugars ex) glucose Amino acids OUT of Cell VESICLE fuses with P.M Macromolecules ACTIVE Exocytosis ACTIVE Endocytosis i) Phagocytosis Into Cell Vacuole formation Cells, Sub-cellular materials ii) Pinocytosis Into Cell Vesicle Formation Smaller molecules, liquids iii) Receptor Mediated Into Cell Receptor Protein, PM to form vesicle ex: hormones, cholesterol Pump Proteins (Facilitated) AGAINST Gradient Carrier Protein & ATP Other sugars, amino acids, ions ACTIVE ACTIVE ACTIVE Fig 4.13 pg 79 Look at picture & Make own notes Receptor Mediated Endocytosis BIG A IDEAS form of pinocytosis Very Specific Used for vitamins, peptide hormones, lipoproteins transport of Cholesterol Used to move substances IN & to TRANSFER substances between cells (eg move from mother’s blood to baby’s blood at placenta) 1. Solute binds to receptor & receptors gather Formation of a coated pit with fibrous protein 2. Vesicle forms & fibrous protein covering is released 3a. Vesicle releases solute into cytoplasm b. Vesicle fuses with lysosome for break down c. Vesicle transports solute to other location 4. Receptors & Membrane of vesicle return to PM Ex. Hyper-Cholesterolemia Ex. Hyper-Cholesterolemia Genetic Disorder Low density lipoproteins (LDLs) transport cholesterol in the blood Reduced # or Defective LDL receptors on PM Cholesterol can’t enter cells normally & builds up in arteries RESULT: High Blood Pressure, Blocked arteries, Heart Attacks