bio2ch7 - Chapter 7 Cellular Pathways that Harvest Chemical...

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Chapter 7 Cellular Pathways that Harvest Chemical Energy 1) Energy and Electrons from Glucose a) Glucose is the most common fuel for cells b) Other foods are usually broken down to glucose molecules c) Energy is obtained through the oxidation of glucose 2) Metabolic Pathways a) Chemical transformations are not simple b) Specific enzymes catalyze each step c) All living organisms have similar pathways d) The organelles of eukaryotes house specific sets of metabolic reactions e) Regulating key enzymes in the pathway controls its operation 3) Metabolizing Glucose a) Process traps free energy b) Overall equation is i) C6H12O6 + 6O2 => 6CO2 + 6H2O + energy ii) Multi-step process iii) Energy captured in ATP iv) Overall reaction is highly exergonic 4) Making ATP a) Substrate-level phosphorylation i) A phosphate group is transferred directly to ADP from a phosphate bearing substrate b) Oxidative phosphorylation i) ATP is synthesized by ATP synthase ii) Uses the energy of a proton (H+) gradient iii) Respiratory chain in the mitochondria 5) Oxidation Reduction (Redox) Reactions a) Reactions in which one or more electrons are transferred between substances b) Reduction – the gain of electrons c) Oxidation – the loss of electrons d) Transfer of electrons = the transfer of 2 hydrogen atoms i) 2 H+ + 2e- ii) Reducing agent iii) Oxidizing agent 6) Oxidation and Reduction are Coupled 7) NAD is an Energy Carrier a) Two forms i) Oxidized (NAD+) ii) Reduced (NADH) (1) NAD+ + 2H => NADH + H+ iii) The oxidation of NADH by O2 (1) NADH + H+ + ½ O2 => NAD+ + H2O 8) Releasing Energy from Glucose a) Glycolysis and cellular respiration
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i) Oxygen is the final electron acceptor b) Glycolysis and fermentation i) Oxygen is not available 9) Glycolysis a) 10 step process i) First five steps: energy input ii) Second five steps: harvest energy b) Step 1 i) Glucose enters cell, immediately phosphoralated; ATP transfers a phosphate to the 6-carbon sugar glucose ii) Chymase is an enzyme that catalyzes the transfer of a phosphate group from one molecule to another (1) ATP to Glucose c) Step 2 i) Glucose 6-phosphate is rearranged to form its isomer, fructose 6-phosphate d) Step 3 i) A second ATP transfers a phosphate to create fructose 1,6-bisphosphate
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This note was uploaded on 04/07/2008 for the course BIOL 2180 taught by Professor Harmich during the Spring '08 term at Toledo.

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bio2ch7 - Chapter 7 Cellular Pathways that Harvest Chemical...

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