HL Topic 7 6 Enzymes Metabolic Pathways n

HL Topic 7. 6 Enzymes

Metabolic Pathways n n 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 n n n ______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 n n n Ex. Krebs cycle and Calvin cycle Catabolic or Anabolic? n _______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 _______

Induce Fit Model n n n 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 n n n _________– 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 n n 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 n n 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 Ø Ø _________– chemical substance that reduces or completely prevents the function of an enzyme Some enzyme inhibitors are ______ and some are _______

Competitive Inhibitor n n _______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 n n 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 n n ________– 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 n n Enzyme has two sites; ____and ______ When end product of pathway is _____ it can encounter and bind the _______of the 1 st enzyme in the pathway This changes the conformation of the enzyme which _____ or ______ the reaction Ensures no _____of end product or intermediate products

Allostery Ø § § 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)