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Unformatted text preview: 1 UNIT TWO: THE CELL Chapter Nine: Cellular Respiration: Harvesting Chemical Energy Chapter Nine: Cellular Respiration: Harvesting Chemical Energy Chapter Nine: Cellular Respiration: Harvesting Chemical Energy Chapter Nine: Cellular Respiration: Harvesting Chemical Energy (Text from Biology , 6 th Edition, by Campbell and Reece) Cellular Respiration: Harvesting Chemical Energy (Chapter Nine) THE PRINCIPLES OF ENERGY HARVEST Cellular Respiration and Fermentation are Catabolic, Energy-Yielding Pathways Recall that catabolic pathways are those that release stored energy by breaking down complex molecules. Fermentation Fermentation Fermentation Fermentation is a catabolic process that partially breaks down sugar without the help of oxygen. The most efficient catabolic pathway is cellular cellular cellular cellular respiration respiration respiration respiration, in which oxygen is consumed as a reactant along with the organic fuel. In eukaryotic cells, cellular respiration occurs in mitochondria. The purpose of cellular respiration is to convert food (organic molecules such as glucose) into ATP that can be used for cellular work. Cells Recycle the ATP They Use For Work ATP, adenosine triphosphate, is highly important in bioenergetics. Remember that the triphosphate tail of ATP has three negatively charged phosphate groups close together, which causes ATP to be extremely unstable, allowing it to store energy. When enzymes transfer phosphate groups from ATP to other compounds, these compounds are said to be phosphorylated. Phosphorylation allows a molecule to undergo a change that performs work, and the molecule will lose its phosphate group in the process. Most cellular work involves ATP being transformed to ADP and a phosphate group. Cells must continue regenerating ATP from ADP and a phosphate group in order to keep working. Redox Reactions Release Energy When Electrons Move Closer To Electronegative Atoms When glucose and other organic fuels are decomposed, electrons are transferred during the chemical reactions. This relocation of electrons releases energy stored in food molecules, and this energy is used to synthesize ATP. In many chemical reactions, one or more electrons, (e- ) are moved from one reactant to the other. These electron transfers are called redox redox redox redox reactions reactions reactions reactions. The loss of electrons from one substance is oxidation oxidation oxidation oxidation, and the addition of electrons is reduction reduction reduction reduction. The electron donor is called the reducing agent reducing agent reducing agent reducing agent, while the electron acceptor is called the oxidizing agent oxidizing agent oxidizing agent oxidizing agent. UNIT TWO: THE CELL Chapter Nine: Cellular Respira Chapter Nine: Cellular Respira Chapter Nine: Cellular Respira Chapter Nine: Cellular Respira (Text from Biology , 6 th Edition, b Redox reactions do not always i electron sharing in covalent bon carbon dioxide and water. Elect oxygen to form carbon dioxide,...
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This note was uploaded on 01/19/2012 for the course CH 101 taught by Professor Sutcliffe during the Spring '08 term at University of Texas at Austin.
- Spring '08
- AP Biology