Comparing Catabolic Pathways Yield Energy By Oxidizing Organic Fuels

1410 Words Dec 14th, 2015 6 Pages
9.1 Catabolic pathways yield energy by oxidizing organic fuels
Catabolic pathways and production of ATP
Fermentation - occurs without O2, is partial degradation of sugars to release energy
Aerobic respiration - uses O2 in breakdown of glucose (or other energy-rich organic compounds) to yield CO2 and H2O and release energy as ATP and heat Of some prokaryotes - doesn’t use O2 as a reactant but it 's a similar process
Cellular respiration - usually used to refer to aerobic process Is exergonic and has a free energy change of -686 kcal/mol of glucose
Redox reactions: oxidation and reduction
Oxidation-reduction - or redox reactions, involve partial or complete transfer of 1 or more electrons from 1 reactant to another
Oxidation - loss of electrons from 1 substance; reduction - addition of electrons to another substance Substance that loses electrons - oxidized and acts as a reducing agent (electron donor) to substance that gains electrons By gaining electrons, substance acts as oxidizing agent (electron acceptor) and becomes reduced
O2 strongly attracts electrons and is 1 of most powerful oxidizing agents
As electrons shift toward more electronegative atom, they give up potential energy Thus, chemical energy is released in redox reaction that relocates electrons closer to O2
Organic molecules with an abundance of hydrogen are rich in “hilltop” electrons that release their potential energy when they “fall” closer to O2
At certain steps in oxidation of glucose,…

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