Exam 1 answer key BIOL 416

Exam 1 answer key BIOL 416 - Exam 1 (2/17/11)...

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Unformatted text preview: Exam 1 (2/17/11) Name__________________________ Biology 416 E-mail_________________________ Short answer portion (20 points). Answer the short answer questions on this sheet of paper. Tear this section from the multiple choice part of the exam hand this paper in separately. 2 (points) The generation of a voltage gradient involves three fundamental elements: a membrane to separate the charge, a Na+/K+ ATP and the ___________ K+ channel _________ (name of other transporter). (4 points) What is the function of the Na+/K+ ATPase? The Na+/K+ ATPase pumps Na+ ions out of the cell and K+ ions into the cell against their gradients. The ATPase creates differences in the ion concentrations across the membrane. E.g. high concentrations of Na+ outside the cell and high concentrations of K+ inside the cell. (4 points) What is the role of the other transporter (see above)? K+ moves down its concentration gradient from the cytosol across the membrane. K+ move through the K+ channel. (6 points) How do these transporters contribute to the voltage gradient? The K+ channel uses this concentration gradient of high intracellular K+ to create an electrical potential across the membrane. The movement of K+ across the membrane will create a positive charge on the exoplasmic side of the membrane and a negative charge on the cytoplasmic side of the membrane. This generates a membrane potential is ~ -60 mV, negative on the cytoplasmic side relative to the exoplasmic face. 1 (4 points) Wikipedia says Extracts containing ouabain have long been used by Somali t ribesmen and other groups to poison hunting arrows. A sufficiently concentrated ouabain dart can bring down a Hippopotamus probably as the result of respiratory and/or cardiac arrest. At sufficient dosage, ouabain is an inhibitor of the Na+/K+ ATPase. What happens to the electrical potential if you apply ouabain to a cell such as a neuron? After application of ouabain the resting membrane potential slowly disappears because the ion concentration gradient required for the membrane voltage dissipates as the ions diffuse down their respective concentration gradients. 2 Choose the most appropriate answer and place your answer on the Scantron sheet. 1. Cl- is transported transcellularly from the basal to the apical surface of parietal cells (stomach lining). Electroneutrality is maintained by the a. movement of bicarbonate anions (HCO 3- ) out of the cell b. presence of a large amount of water in the cytosol c. movement of K + through the K + channel 2. The thickness of the lipid bilayer is dependent upon the a. formation of a liposome b. presence of sphingomyelin, cholesterol and phosphatidyl choline in the membranes c. fluidity of the membrane proteins 3. Chose the statement below that best explains the following: The structure of all biomembranes depends on the chemical properties of phospholipids, whereas the function of each specific biomembrane depends on the specific proteins associated with that...
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This note was uploaded on 05/09/2011 for the course BIOL 416 taught by Professor Gamblin,t during the Spring '08 term at Kansas.

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Exam 1 answer key BIOL 416 - Exam 1 (2/17/11)...

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