Lecture 17 Membrane transport

Lecture 17 Membrane transport - Biol141 Foundations in...

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Biol141 Foundations in Modern Biology Cellular Biology and Genetics Lecture 17 – Wednesday, October 5 th , 2011 Membrane transport Reading: Freeman, Emory 2 nd Ed. Chapter 6 (pages 89-99)
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Learning objectives At the end of this lecture, you will be able to: 1) Predict the movement of solutes or water across a concentration gradient by diffusion or osmosis. 2) Describe the roles of transmembrane transport proteins in the movement of molecules across membranes . 3) Explain the roles of channel and carrier proteins in the process of facilitated diffusion. 4) Discuss the role of pump proteins in active transport across a membane using the Na + /K + -ATPase as an example.
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Three different mechanisms of membrane transport
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1. Biological membranes are selectively permeable— they allow some substances to pass, while others are restricted. Some substances can move by simple diffusion through the phospholipid bilayer. Diffusion is the process of random movement toward the state of equilibrium.
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Small molecules and ions in solution are called solutes , have thermal energy, and are in constant, random motion.
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A difference in solute concentrations creates a concentration gradient . Molecules and ions move randomly when a concentration gradient exists, but there is a net movement from high- concentration regions to low-concentration regions . Diffusion along concentration gradient increases entropy and is thus spontaneous.
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is established once the molecules or ions are randomly distributed throughout a solution. Molecules are still moving randomly but there is no
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Lecture 17 Membrane transport - Biol141 Foundations in...

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