chapter 8 bio 202 - Chapter 8 Catabolic pathways or...

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Chapter 8: - Catabolic pathways or breakdown pathways (cellular respiration) - Anabolic pathways consume energy to build complicated molecules from simpler ones (also called biosynthetic pathway) o Ex. Synthesis of a protein from amino acids - Catabolic and anabolic pathways are the downhill and uphill avenues of the metabolic map - Energy released from the downhill reaction of catabolic pathways can be stored and used to drive the uphill reactions of anabolic pathways - Bioenergetics: the study of how energy flows through living organisms Forms of Energy - Energy is capacity to cause change. - Chemical energy: potential energy available for release in a chemical reaction - During a catabolic reaction, atoms are rearranged and energy is released resulting in a lower energy breakdown products The Laws of Thermodynamics: - Open system: energy and matter can be transferred between the system and its surroundings o Organisms are open systems o They absorb energy (light or chemical energy) in the form of organic molecules and release heat and metabolic waste products such as carbon dioxide to the surroundings First Law of Thermodynamics - Energy of the universe is constant. Energy can be transferred and transformed but it cannot be created or destroyed. - Principle of conservation of energy Second Law of Thermodynamics - Most usable forms of energy are at least partly converted to heat, which is the energy associated with the random motion of atoms or molecules - A system can put heat to work only when there is a temperature difference that results in the heat flowing from a warmer location to a cooler one - Every energy transfer or transformation increases the entropy of the universe - Increased entropy is evident in physical disintegration of a system’s organized structure. o Much of the increasing entropy of the universe is less apparent (by increasing amounts of heat and less ordered forms of matter - In order for a process to occur, it must increase the entropy of the universe - The word spontaneous does not mean it will occur quickly - For a process to occur spontaneously, it must increase the entropy of the universe Biological Order and Disorder - Cells create ordered structures from less organized starting materials - As catabolic pathways break molecules down, animal releases CO2 and water, small molecules that possess less chemical energy than the food o The depleted chemical energy is accounted byt the heat generated by the metabolism - Energy flows into an ecosystem in the form of light and exits in the form of heat.
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