Chapter 11 Bio107
Washington State University Vancouver
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This 3 page Class Notes was uploaded by Lorina Tomceac on Thursday October 8, 2015. The Class Notes belongs to Bio107 at Washington State University Vancouver taught by Dr. Michel Berger in Fall. Since its upload, it has received 39 views. For similar materials see biology in Science at Washington State University Vancouver.
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Date Created: 10/08/15
Bio 107 Chapter 8 lecture O 90 O 90 O 90 O 90 O 90 Metabolism Metabolic pathways gt MULTISTEP PROCESS INVOLVING MULTIPEL ENZYMES AND INTERMIDIATE PRODUCTS Catabolic pathway gt Breakdown of complex molecules gt Stored energy can be used for work Anabolic pathway gt Assembly of complex molecules gt Require energy for work I Which is an example of a catabolic pathway Respiration breakdown of organic matter in order to use it for work or energy Energy gt Cells use energy stored in organic molecules to perform work gt Energy capacity to do work gt Two laws of thermodynamics 1 Energy can be transferred but never created or destroyed a Energy is always converted never manufactured 2 Every energy transfer increases the entropy of the universe a Entropy is disorder b Heat is a disordered form of energy c A building will become dilapidated over time if its not maintained Most chemical energy transformation results in a conversion to heat gt 25 of the chemical energy stored in gas is transferred into a moving car gt 75 is lost as heat Free energy proportion of a systems energy to perform work d61t GG na1 Ginitia1 Measure of a systems instability Loss of free energy as a system moves towards equilibrium A G L Gfmal Gintial More free energy higher G Less stable I Greater work capacity I In a spontaneous change the free energy of the system decreases The released free energy can be harnessed to do work Exergonic reactions gt Free energy is released gt A Glt0 Endergonic reaction VVVVV gt gt Free energy is absorbed A Ggt0 Reaction move toward equilibrium gt gt Cells often use an exergonic reaction to drive an endergonic reaction Product of one reaction becomes the reactant I Energy is transferred in a series of step wise exergonic reaction EX A multistep open hydroelectric system ATP adenosine triphosphate VVVV Ribose carbohydrate adenine nitrogenous base and 3 phosphate groups Bond between phosphate group can be broken ADP adenosine diphosphate Phosphates are negatively charged I Similar charges are repulsive analogy think of a compact sprong I ATP is turned into ADP through a hydrolysis reaction ATP I Glutamic acid is phosphorylated I Phosphorylated intermediate is more reactive ADP is continually regenerated into ATP I Turnover rate pf 20 million per second per cell in muscle cells I Endergonic reaction I deltG 73 I Cellular respiration provides the energy the oxidation of glucose to C02 and H20 is highly exergonic deltG686 kcalmol How come glucose does not spontaneously combust I Glucose molecules lack the activation energy at room temperature Enzymatic reaction I Hydrolysis of sucrose is a spontaneous exergonic reaction I Enzymes speed up chemical reaction I Enzymes are catalysts 0 Change the chemical rate of a reaction without being consumed by the reaction 0 Enzymes speed things up 0 It lowers the barrier of the activation energy energy required to start a reaction 0 Chemical bonds only break down when a molecule has absorbed enough energy to become unstable Fire y luciferase catalyze the reaction luceferin ATP I adenylluceferin phosphate I The next reaction occurs spontaneously I What is the role of luciferase 0 Luciferase lowers the activation energy of the reaction Enzymes can only speed up a reaction that would occur spontaneously gt zsn4gtwgtd Enzymes are substrate specific Substrate enter active site Substrate are held in the active site by weak interactions Substrates are converted to products Products released Active site is available for new substrates echanisms to lower activation energy Template for substrate to come together I Stretch or bend molecules gt Factors that effect enzyme activity I Environmental conditions Temperature 0 At high temp enzymes denature and are not effective pH Salt concentration I Cofactors Non protein helpers 0 Metal ions zinc iron amp copper O Vitamins considered a coenzyme I Inhibition Molecules bind to a site on the enzyme Often irreversible if covalent bond occurs Toxins is a competitive inhibitor competitively bind to the active site Competitive inhibition 0 Increase concentration of substrate to overcome inhibition Non competitive inhibition 0 Bind to region other than active site Used to regulate cell metabolism I Regulation of enzyme activity Turn on or off the synthesis of a specific enzyme Control the activity of synthesized enzymes O 000 Allosteric regulation Activating or inhibiting molecule binds to a regulatory site ATP hydrolysis ATPinhibitor and ADP activator act as allosteric regulators Increase in concentration of ADP activates the synthesis of ATP If ATP concentration exceeds demand increased ATP concentration inhibits ATP synthesis Self regulating negative feedback loop gt Feedback inhibition I The metabolic pathway is switched off by the end product I The end product binds to the allosteric site