chapter5b Membrane Dynamics 2

chapter5b Membrane Dynamics 2 - Chapter 5b Membrane...

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Unformatted text preview: Chapter 5b Membrane Dynamics Energy Transfer in Living Cells Figure 5-16 ATP Secondary active transport Primary active transport Metabolism The chemical bond energy is converted into high-energy bonds of ATP through the process of metabolism. The energy in the high-energy phosphate bond of ATP is used to move K+ and Na+ against their concentration gradients. This creates potential energy stored in the ion concentration gradients. The energy of the Na+ gradient can be used to move other molecules across the cell membrane against their concentration gradients. Energy is imported into the cell as energy stored in chemical bonds of nutrients such as glucose. Glucose Pyruvate CA cycle Heat H2O CO2 ADP+Pi O2 High [K+] Low [Na+] Na+ Na+ Glycolysis ETS K+ K+ 2 Cl– Low [K+] High [Na+] Glucose ATP ATP ETS = Electron transport system = Citric acid cycle CA cycle KEY Carrier-Mediated Transport • Specificity • Competition • Saturation • Transport maximum Carrier-Mediated Transport Competition Figure 5-17 Carrier-Mediated Transport Competition Figure 5-18 (b) Maltose (a) The GLUT transporter Maltose Glucose Glucose GLUT transporter Intracellular fluid Extracellular fluid Carrier-Mediated Transport Saturation Figure 5-19 Vesicular Transport • Phagocytosis • Cell engulfs bacterium or other particle into phagosome • Endocytosis • Membrane surface indents and forms vesicles • Active process that can be nonselective ( pinocytosis ) or highly selective • Potocytosis uses caveolae • Receptor-mediated uses clathrin-coated pits Phagocytosis Figure 5-20 1 Bacterium Lysosome Phagocyte The phagocytic white blood cell encounters a bacterium that binds to the cell membrane. The phagocyte uses its cytoskeleton to push its cell membrane around the bacterium, creating a large vesicle, the phagosome. The phagosome containing the bacterium separates from the cell membrane and moves into the cytoplasm. The phagosome fuses with lysosomes containing digestive enzymes. The bacterium is killed and digested within the vesicle. 2 3 4 5 Phagocytosis Figure 5-20, step 1 1 Bacterium Lysosome Phagocyte The phagocytic white blood cell encounters a bacterium that binds to the cell membrane. Phagocytosis Figure 5-20, steps 1–2 1 Bacterium Lysosome Phagocyte The phagocytic white blood cell encounters a bacterium that binds to the cell membrane....
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This note was uploaded on 01/03/2012 for the course BIO 308 taught by Professor Acbrown during the Spring '10 term at Portland.

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chapter5b Membrane Dynamics 2 - Chapter 5b Membrane...

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