BIOL 1411 1st Edition Lecture 11 Outline of Last Lecture 1 Energy transformation 2 Enzymes characteristics 3 How enzymes work Outline of Current Lecture 1 Finish up enzymes from last lecture 2 Overview of glucose 3 3 metabolic pathways 4 Redox overview 5 Discuss glycolysis in detail Current Lecture continuation of how enzyme activities are regulated from last lecture Allosteric Regulation type of noncompetitive regulation o A type of noncompetitive regulation o Enzymes can exist in more than one shape Active form can bind substrate Inactive form cannot bind substrate o Most allosteric enzymes are proteins with quaternary structure Catalytic subunit with active site These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Regulatory structure to which a small molecule effector can bind Effector molecule induces change in shape in enzyme Effectors can wither inhibit or activate an enzyme with a certain range reaction rates for allosteric enzymes are sensitive to small changes in substrate concentration allosteric enzymes important for regulating metabolic pathways very sensitive to small changes in concentration of noncompetitive inhibitors metabolic pathway navigation first reaction commitment step other reactions then happen in sequence when enough end product is present whole pathway will than turned off feedback inhibition end product inhibition o final product acts as a noncompetitive inhibitor of the first enzyme the following image is a key concept of living systems Physical environment also effects enzyme activity o Ph Every enzyme is most active at a particular pH pH influences the ionization of functional groups this affects folding and thus enzyme function o temp every enzyme has an optimal temperature High temp noncovalent bonds begin to break Enzyme can lose its tertiary structure and become denatured end of lecture 10 notes Lecture 11 Chapter 9 bioenergetics Fuels o Carbon based molecules whose stored energy can be released for use Energy is released through oxidation reactions that breakdown the fuel molecules into simpler molecules such as CO2 Glucose o Most common fuel in organisms o Cell metabolism converts other molecules into glucose or intermediates of glucose oxidation o Polymers of glucose are used by plants and animals for energy storage Principles governing metabolic pathways o Complex chemical transformations occur in a series of reactions o Each reaction is catalyzed by a specific enzyme o Metabolic pathways are similar in all organisms o In eukaryotes metabolic pathways are compartmentalized in organelles o Each pathway is regulated by key enzymes usually allosteric mechanisms Three metabolic pathways are involved in harvesting the energy of glucose o Glycolysis Glucose converted to pyruvate Most ancient of the processes and is the starting point for both of the other processes o Cellular respiration Aerobic O2 present and converts pyruvate into H2O and CO2 leads to synthesis of much ATP complete oxidation waste products are H2O and CO2 net energy trapped per glucose is 32 ATP o Fermentation Anaerobic O2 absent and converts pyruvate into lactic acid or ethanol CO2 produces little ATP Incomplete oxidation Waste products are lactic acid or ethanol and CO2 Net energy trapped is 2 ATP All glucose oxidation reactions involve electron transfer reactions REDOX reactions o Reduction gain electrons o Oxidation losing electrons o Redox reactions also occur if hydrogen atoms are gained or lost o Oxidation and reduction occur together o Refer to oxidation reduction slides if more information needed o Glucose oxidation releases chemical energy in cells Glucose oxidized oxygen becomes reduced All electrons part of H atom in glucose are transferred to molecules of oxygen to form water Energy from bonds of glucose is transferred If all energy was released in one step blazing heat and a fried cell Series of reactions each releases a small amount of energy that can be captured for endergonic reactions Nico o Nicotinamide dinucleotide production Controlled steps of glucose reactions are catalyzed by enzymes Coenzyme NAD is a key electron carrier in redox reactions NAD oxidized o Receives electron from glucose NADH reduced o Carries electron from glucose to other molecules in the mitochondria ultimately to the O2 like ATP and ADP it cycles back and forth between one state and the other o Glycolysis Discussed before Starting point for all energy harvesting processes Inputs Glucose C6H12O6 2 NAD 2 ADP 2P i Outputs 2 molecules of pyruvate C3H4O3 2 NADH has those other 4 H atoms from glucose 2 ATP net 10 enzyme catalyzed reactions Reactions 1 5 o Energy investment o Adding P to glucose Reactions 6 10 o Energy payout o In NADH and 2 ATP net reactions 1 10