Biology exam 2 - Chapter 8 Metabolism is the totality of an...

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Chapter 8 Metabolism is the totality of an organism’s reactions. Each step in the metabolic pathway is catalyzed by a specific enzyme. Catabolic pathways release energy by breaking down complex molecules to simple compounds. Cellular respiration is catabolic. Anabolic pathways consume energy to build complex molecules out of smaller ones. Also called biosynthetic pathways. Energy released from catabolic pathways can be stored and used to run anabolic pathways. Bioenergetics is the study of how energy flows through living organisms. Energy is the capacity to cause change. Kinetic energy is associated with the relative motions of objects. Moving objects can perform work by imparting motion to other objects. Heat or thermal energy is the kinetic energy associated with the random movement of atoms or molecules. An object that is not moving can still possess energy. Energy that is not kinetic is called potential energy. Matter possesses potential energy because of its location or structure. Molecules have potential energy is the form of the arrangement of electrons in their bonds. Chemical energy is the potential energy available for release in a chemical reaction. Glucose is high in chemical energy. During a catabolic reaction, some bonds are broken and others are formed, resulting in lower energy breakdown products. Biochemical pathways allow cells to release energy from food and power life processes. Thermodynamics is the study of energy transformations that occur in a collection of matter. The matter under study is called a system. Isolated systems cannot exchange energy or matter with their surroundings. Open systems can. Organisms are open systems. They absorb energy and release heat and metabolic waste products to the surroundings. First law of thermodynamics: energy can be transferred and transformed but it cannot be created or destroyed. Also called the principle of conservation of energy. During every energy transformation, energy is lost as heat. Not 100% efficient.
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Each energy transfer or transformation makes the universe more disordered. The quantity used to measure disorder is called entropy. Second law of thermodynamics: every energy transfer or transformation increases the entropy of the universe. For a process to occur on its own without help it must increase the entropy of the universe. A process that can occur without an input of energy is called a spontaneous process. Nonspontaneous means that the process cannot occur on its own; energy must be added to the system. Living systems increase the entropy of their surroundings. They take in organized forms of matter and energy from the surroundings and replace them with less ordered forms. Energy flows into most ecosystems in the form of light and exits in the form of heat.
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