BIO 101 1st EditionLecture 11Outline of Last LectureI. Cytoskeletona. Microtubulesb. Microfilamentsc. Intermediate filamentsII. The Cell Surfacea. Cell Wallsb. Gylcocalyxc. Intercellular JunctionsOutline of Current LectureI. Metabolisma. Metabolic PathwaysII. Classified Energeticsa. Catabolic pathwaysb. Anabolic pathwaysIII. Energya. Kineticb. Potential IV. ThermodynamicsV. Chemical reactionsa. Exergonicb. EndergonicChapter 8- Introduction to MetabolismMetabolism: all of an organism’s chemical processes- There are thousands of chemical reactions in the cell- They are coordinated and integrated with one another - Organized into metabolic pathwaysMetabolic pathways- an ordered series of chemical reactions in which the PRODUCT of one reaction becomes the REACTANT for the next reaction a stepwise process, an example of a pathwayTwo Basic Types of Pathways- Classified EnergeticsBIO 101 1st Edition1. Catabolic pathways- pathways that release energy by breaking down complex molecules into simpler molecules Complex Simple*release energy*2. Anabolic pathways- pathways that consume energy to build complex molecules starting with simple moleculesSimple Complex*consumes energy*Energy- exists in two different forms;1. Kinetic energy- energy of motion2. Potential energy- energy of positionEnergy can be changed from one form to another formEx: chemical potential energy in gasoline can be transformed into kinetic energy to move pistons in a carThermodynamics= study of energy transformations1 st Law of Thermodynamics- energy can be transferred or transformed but can NOT be created or destroyed2 nd Law of Thermodynamics= every energy transfer makes the universe more disordered Energy with Regard to Chemical ReactionsEnthalpy (H)= total potential energy of a molecule= BOND EnergyEach chemical reaction proceeds with a change in enthalpy In chemical reaction, reactant is changed into the productReactant (H) Product (H)- If there is more bond energy in the product than is in the reactant, then energy has to be put in to make the reaction go- If there is less bond energy in the product than in the reactant, then energy is released by the reactionEntropy (S)= quantitative measure of disorderSystem may become more ordered , but only at the expense of the surroundings.BIO 101 1st EditionAs with H (bond energy), each chemical reaction proceeds with some change in entropy*Both the H and the S factors must be considered in the energy of chemical reactionsEnergy with Regard to Chemical Reactions- In a chemical reaction, reactant molecules are changed into product moleculesReactants products- Each chemical reaction proceeds with a change in FREE ENERGY (G)= amount of energy available to do work- FREE ENERGY includes both enthalpy and entropy factors as shown in this equation - The of a chemical reaction is important because it determines if the reaction will be spontaneous or not- There are two kinds of chemical reactions with regard to 1. Exergonic reactions2. Endergonic reactionsExergonic Reactions VS. Endergonic ReactionsSpontaneous Not spontaneousReactants have MORE bond energy (H) than products: energy is releasedReactants have LESS bond energy (H) than products: energy is consumedS tends to increase during the reaction (products are more disordered)S tends to decrease during the reaction (products are more ordered)(-) G is maximum amount of work that reaction can do(+) G is minimum amount of work requiredto make a reaction
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