SI session Oct. 9 Ch. 8 and 9 answers

SI session Oct. 9 Ch. 8 and 9 answers - Kaiser Imam October...

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Kaiser Imam October 9, 2007 BIOL 215 SI Session Chapters 8 and 9 Chapter 8: Transport Processes 1. Order the molecules on the following list according to their ability to diffuse through a lipid bilayer, from most to least permeable. Explain your order. a. Ca +2 CO 2 b. CO 2 H 2 O c. Ethanol Ethanol d. Glucose Glucose e. RNA Ca +2 f. H 2 O RNA The rate of diffusion depends on the size and polarity of the molecule. For example, small molecules like CO 2 , H 2 O, and ethanol can pass through the plasma membrane easily. Larger molecules like glucose or ions like Ca +2 need transport proteins to move them across the membrane. Finally, the RNA molecule is so large that it cannot pass through the membrane. Rather, it must be transported within a vesicle by endocytosis or exocytosis. 2. What is the difference between a carrier protein and a channel protein? A carrier protein has to physically bind to a solute on one side of a membrane and change conformation to release the solute on the other side. Channel proteins are different because they form a usually hydrophilic channel through which solutes can pass without having to change the conformation of the channel protein. 3. Describe each of the following types of carrier proteins: 1) Uniporter Transports a single molecule of solute across the membrane at the time. An example is the GLUT1 glucose transporter in erythrocytes. 2) Symporter Transports two solutes in the same direction. An example is the Na + /Glucose symporter. 3) Antiporter Transports two solutes in opposite sides of the membrane. An example is the Na + /K + antiporter. 1
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4. List 3 reasons why cells utilize active transport: 1) Aids in the uptake of nutrients from the environment or surrounding fluid 2) Allows wastes and other substances to be removed from the cell or organelle, even when the concentration outside is greater than that inside 3) Enables the cell to maintain constant nonequilibrium intracellular concentrations of certain ions even against their concentration gradient (ex: Na + , K + , Ca +2 , H + , Cl - ) 5. What is the difference between direct and indirect active transport? In direct active transport the movement of a solute molecule or ion is directly coupled to an exergonic chemical reaction such as the hydrolysis of ATP. Indirect active transport depends on the simultaneous transport of two solutes, with the movement of one solute down its gradient driving the movement of the other up its gradient. 6. Describe the following types of ATPases involved in active transport: P-Type ATPases: are reversibly phosphorylated by the phosphate molecule from ATP as part of the transport mechanism F-Type ATPases: generates H + gradient that drives ATP synthesis. The pumps essentially run in reverse and function as ATP synthases, producing ATP as well as consuming it. ABC-type ATPases:
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This note was uploaded on 09/29/2009 for the course BIO 215 taught by Professor Diiulio during the Spring '09 term at Case Western.

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SI session Oct. 9 Ch. 8 and 9 answers - Kaiser Imam October...

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