Energy211S - Energy Enzymes and Metabolism 1 Thousands of...

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Energy, Enzymes and Metabolism - 1 Thousands of chemical reactions occur in our cells and tissues to keep us alive (and hopefully healthy). Monomers are assembled into the polymers we need for cell structure and function. Fuel molecules are oxidized during cell respiration to provide the energy to do cell work. Substances are synthesized and then secreted from specialized cells to be used in other parts of the organism. All of these chemical reactions are coordinated and controlled in orderly processes that collectively comprise the metabolism of a living organism. Within a cell and within an organism, the thousands of chemical reactions of metabolism are interconnected in ways that maintain the organism's homeostasis. The field of systems biology analyzes and often uses computer-generated models to help us understand the thousands of metabolic pathways within cells, the interactions between pathways and the regulation of chemical processes within and between cells. Computer Model of Homeostasis and the Complex Interactions of Metabolism Fortunately, the organism does not have to consciously direct these activities. None-the-less, biology students need to spend some time discussing how the chemical reactions that make an organism "work" take place, and the energy transformations that occur. Metabolism involves both assimilation of and degradation of molecules. Those chemical reactions that build up molecules are called anabolism and use anabolic pathways. (A metabolic pathway is a defined sequence of chemical reactions with a specific starting molecule, a set of intermediates and a specific final product.)
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Energy, Enzymes and Metabolism - 2 Most often, anabolic reactions combine smaller molecules into larger molecules, such as the synthesis of polysaccharides from monosaccharide monomers. Anabolic processes are often energy consuming processes. (Anabolic steroids are synthetic steroids that promote muscle development along with a host of negative side effects.) The chemical reactions that break down molecules follow catabolic pathways, and are catabolisms. The chemical reactions of digestion are catabolic as is the process of cell respiration, an energy releasing catabolic pathway. It is typical in cells to "couple" energy releasing catabolic pathways with anabolic reactions. ATP is the primary energy coupler in cells. {See later} Energy, Metabolism and Thermodynamics The purpose of this chapter is to examine some of the mechanisms common to metabolic pathways. Since metabolism involves energy gains and losses, it is helpful to have a common knowledge base about energy. We will briefly review the physical laws that govern energy flow, how energy flow relates to chemical reactions and how living organisms control the chemical reactions that occur in their cells and tissues. Since enzymes catalyze our chemical reactions and additional mechanisms regulate the activity of enzymes, it's important to take a look at enzyme activity, too. Feedback on materials being synthesized and degraded in cells is also important.
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Energy211S - Energy Enzymes and Metabolism 1 Thousands of...

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