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HL Topic 7.6 Enzymes. Metabolic Pathways. Chemical changes in living things often occur with a number of ____________________ Each stage has its own _________ ________ pathways _____________ molecules and release energy _____________ pathways _____________ molecules. Chain Pathways.
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Metabolic Pathways • Chemical changes in living things often occur with a number of ____________________ • Each stage has its own _________ • ________ pathways _____________ molecules and release energy • _____________ pathways _____________ molecules
Chain Pathways • ___________is specific to ____________. Sub. 1 changes to product 1. • ________is specific to product 1 which now becomes _________ and is converted to product 2. • __________ is specific to product 2/substrate 3 and converts it to the __________. • Ex. Glycolysis • Catabolic or Anabolic?
Cyclic Pathways • _____________enters the cycle • ____________combines the regenerated intermediate (inter.) 4 with the _________ __________to produce inter.1 • Enzyme 2 is ________to inter.1 and converts it to inter. 2 • _________is specific to inter. 2 which it converts to the product and inter. 3 • Enz. 3 + inter. 3 = __________ • Inter. 4 is then used again to ______________ Ex. Krebs cycle and Calvin cycle Catabolic or Anabolic?
Induce Fit Model • Active site is not an ________ for substrate; instead the site _____________to the shape of the substrate • By changing __________of the enzyme, it actually places mechanical stress on the substrate the enables bonds to ________easier • This _________ active site allows for ________ specificity of some enzymes (ex. Proteases being able to dissolve many dif. proteins in detergents)
Activation Energies • __________________– energy that must be gained by a molecule to break bonds and carry out a reaction • _______________– a reaction where the amount of energy given out is greater than the amount needed to start a reaction (activation energy) • __________________– reaction where the amount of energy given off is less than that needed to start the reaction
Exergonic Reaction • Enzymes lower the activation energy needed to ____________________ • Energy gained by the reaction is not different than when ___________; however, since the amount needed to start it is less there is more ___________
Endergonic Reaction • Enzyme lowers the ___________________needed to start this reaction • The amount of free energy at the end of this reaction is not more than the energy needed to start the reaction; overall _____________
Enzyme Inhibition • _________________– chemical substance that reduces or completely prevents the function of an enzyme • Some enzyme inhibitors are ____________and some are ______________
Competitive Inhibitor • _____________and ___________ are chemically very similar • The inhibitor can bind to the ______________of the enzyme • While inhibitor is in the active site enzyme will __________________ • Ex. In the Citric Acid Cycle (Krebs) succinate is converted to fumarate. Malonate binds to the enzyme responsible to the above reaction which inhibits it.
Non-competitive Inhibition • Substate and inhibitor are not ___________________ • Inhibitor binds to the enzyme at ________________than active site. • This changes the _____________ of the enzyme. It may slow or totally prevent the _______________while bound • Ex. - DDT blocks enzymes in nervous system - Anti-biotics block enzymes in bacteria that make cell wall
Below comp. Inhib. ___________will always be binding w/ substrate. _____________ the conc. of substrate lessens the effect of the inhibitor Above non-comp. Inhib. Some enzymes affected and will forever more ___________reaction. Rate _________ and lower.
Allostery and Metabolic Pathways • ________________– when the last product in a metabolic pathway inhibits the enzyme that starts the pathway • _______________– the enzyme that is inhibited by the end product of a reaction
Allostery • Enzyme has two sites; ________and ___________ • When end product of pathway is _________ it can encounter and bind the ______________of the 1st enzyme in the pathway • This changes the conformation of the enzyme which _____ or ______ the reaction • Ensures no _________of end product or intermediate products
Allostery • Examples • ATP inhibition of phosphofructokinase (enzyme that drives glycolysis) • Inhibition of ATCase (enzyme that catalyses the first step of pyrimidine synthesis during nucleic acid building)
