questions_for_section_4

questions_for_section_4 - 1)Its powers the active transport...

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Questions for section 4 Name__Darren Pinder___________ Answer in complete sentences. A good hypothesis has explanatory value and makes testable predictions. The chemiosmotic hypothesis proposed by Peter Mitchell was a good hypothesis, and is now a significant part of theory about how cells power themselves . 1. What explanatory value did this hypothesis have (i.e., what was one puzzling phenomena it could explain)? His theory explained how mysterious uncoupling agents work. These agents are weak acids that dissolve in the lipids of the membrane allowing them to bing, or release protons based on the acidity of their surroundings. They are instrumental in shuttling protons across the membrane. 2. What was one testable prediction made by Mitchell’s chemiosmotic hypothesis? The prediction was that mitochondria generate a pH gradient as well as an electrical charge (of about 150 millivolts) across the membrane. 3. Besides making ATP, what are two things cells use proton gradients to power?
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Unformatted text preview: 1)Its powers the active transport of molecules in and out of the cell across the external membrane 2)Bacterial locomotion uses proton gradients. Flagellum in bacteria rotates like a motor that is powered by a proton current through its drive shaft. 4. Many mammals have a specialized form of adipose tissue called brown fat. This tissue is full of mitochondria that are actively running electron transport chains; however, these cells also produce uncoupling agents that prevent these mitochondria from producing significant amounts of ATP. Explain, using thermodynamics, how brown fat helps these mammals to keep warm. This speed tissue can generate heat by "uncoupling" the respiratory chain of oxidative phosphorylation within mitochondria. The process of uncoupling means that when protons transit down the electrochemical gradient across the inner mitochondrial membrane the energy from this process is released as heat rather than being used to generate ATP...
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This note was uploaded on 09/21/2011 for the course BIS 002A taught by Professor Unknown during the Summer '09 term at UC Davis.

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