Chapter 9 Biology Notes

Chapter 9 Biology Notes - Chapter 9 Notes- Cellular...

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Chapter 9 Notes- Cellular Respiration (Harvesting Chemical Energy) 9.1 Catabolic pathways yield energy by oxidizing organic fuels 1. Catabolic Pathways and Production of ATP a. One catabolic process, fermentation , is a partial degradation of sugars that occurs without the use of oxygen. b. The most prevalent and efficient catabolic pathway is aerobic respiration , in which oxygen is consumed as reactant along with the organic fuel. The cells of most eukaryotic and many prokaryotic organisms can carry out aerobic respiration. c. Anaerobic respiration is a process used by prokaryotes that harvests chemical energy without using any oxygen. d. Aerobic respiration equation: organic compounds + oxygen = carbon dioxide + water + energy e. The breakdown of glucose is exergonic and has a free energy change of –686 kcal. 2. Redox Reactions: Oxidation and Reduction a. The transfer of elections during the chemical reactions decomposes glucose and other organic fuels and yields energy. The relocation of electrons releases energy stored in organic molecules, and this is used to synthesize ATP. b. Redox reactions are the transfer of one or more electrons from one reactant to another. c. Oxidation is the loss of elections from one substance, and the addition of electrons to another substance is called reduction. d. The reducing agent is the electron donor; the oxidizing agent is the electron acceptor. e. The reaction between methane and oxygen on page 164 is an example of a redox reaction that changes the degree of electron sharing in covalent bonds. The carbon in CH 4 becomes oxidized in the CO 2 and the O 2 becomes reduced in the 2H 2 O. f. Oxygen is one of the most potent of all oxidizing agents because it is so electronegative. g. The more electronegative the atom (the stronger its pull on electrons), the more energy is required to take an electron away from it. An electron loses potential energy when it shifts from a less electronegative atom toward a more electronegative one. 3. Oxidation of Organic Fuel Molecules During Cellular Respiration h. Cellular respiration: C 6 H 12 O 6 + 6O 2 = 6CO 2 + 6H 2 O + Energy (glucose is oxidized and oxygen is reduced) i. In general, organic molecules that have an abundance of hydrogen are excellent fuels because their bonds are a source of electrons with potential energy. j. The important point for summary equation for respiration is that the energy state of the electron changes as hydrogen (with its electrons) is transferred to oxygen. The oxidation of glucose transfers electrons to a lower energy state, liberating energy that becomes available for ATP synthesis. k. In the main energy foods, only the barrier of activation energy holds back the flood of electrons to a lower energy state. 3.
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Chapter 9 Biology Notes - Chapter 9 Notes- Cellular...

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