BioCh8 - Biology Notes Chapter 8 An Introduction to...

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Biology Notes Chapter 8 An Introduction to Metabolism The Energy of Life Abstract (Overview) An organism's metabolism, Free-energy change of a reaction, ATP powers cellular work, Enzymes, Regulation of enzymes Concept 8.1 – Organism's Metabolism *Metabolism; The totality of an organism's chemical reactions. It is an emergent property of life that arises from interactions between molecules within the orderly environment of the cell. As a whole, it manages the material and energy resources of the cell. Organization of the Chemistry of Life into Metabolic Pathways Metabolic Pathway; Begins with a specific molecule – which is then altered in a series of defined steps, resulting in a certain product. Each step of the pathway is catalyzed by a specific enzyme. A [Starting Molecule] → B → C → D [Product] A to B involves Enzyme/Reaction 1 B to C involves Enzyme/Reaction 2 C to D involves Enzyme/Reaction 3 Catabolic Pathways; Metabolic pathways that release energy by breaking down complex molecules to simpler compounds - “breakdown pathways” - A major pathway of these is cellular respiration, in which the sugar glucose and other organic fuels are broken down in the presence of oxygen to carbon dioxide and water. [Pathways can have more than one starting molecule and/or product] Anabolic Pathways; Metabolic pathways that consume energy to build complicated molecules from simpler ones; sometimes called “biosynthetic pathways”. An example is the synthesis of a protein from amino acids. ^^Both pathways are the “downhill” and “uphill” avenues of the metabolic map. Energy released from the downhill reactions of catabolic pathways can be stored and then used to drive the uphill reactions of anabolic pathways. Forms of Energy Energy; Capacity to cause change. Important in everyday life, because some forms of energy can be used to “do work” - which is to move matter against opposing forces, such as gravity and friction. In another way, energy is the ability to rearrange a collection of matter. (An example is changing pages of a book, in which cells expend eneergy in transporting certain substances across
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BioCh8 - Biology Notes Chapter 8 An Introduction to...

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