BioG 102 Final Essays - Bio Final Essay Questions 1....

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Bio Final Essay Questions 1. Cellular work: a. Chemical : Calvin cycle: Uses ATP and NADPH to convert CO2 to sugar. Anabolic: builds sugar from smaller molecules. Source of Energy: Total 9 ATP; 6 NADPH as reducing power for adding high E e- to make the sugar. Steps: 1. 3 molecues of CO2 in one at a time. 2. Carbon is fixed by rubisco 3. ATP phosphorylates the intermediate (gives Pi group); NADPH reduces this to G3P by donating a pair of e-. One G3P sugar released. 4. 3 ATP regenerate RuBP by recycling 5 GP3. 2. ATP: a. Provides energy for endergonic reactions: Hydrolysis of Pi from ATP is exergoinic releasing 7.3 kcal/mol. With enzymes, cell couples energy of ATP hydrolysis directly to endergonic processes. Transfers a phosphate group from ATP to another molecule. Recipient is phosphorylated intermediate which is more reactive than original reactant molecule. Summary: Pi from ATP molecule, and phosphorylated molecule undergoes change that performs work. 3. Negative feedback: feedback regulation in which accumulation of an end product of a process slows that process. Change in variable being monitored triggers control mechanism to counteract further change in same direction. Effector response reduces initial stimulus and eventually response ceases. a. Multistep biochemical pathway : Cell’s breakdown of sugar in cell respiration generates chemical energy in the form of ATP. Excess accumulation of ATP inhibits an enzyme near beginning of the pathway. Phosphofructokinase: allosteric enzyme that catalyzes step 3 of glycolysis. Inhibited by ATP. As ATP +, inhibition of enzyme
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This note was uploaded on 01/10/2009 for the course BIO G 102 taught by Professor Walcott during the Spring '08 term at Cornell University (Engineering School).

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BioG 102 Final Essays - Bio Final Essay Questions 1....

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