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ENERGY Laws of Thermodynamics (1st/2nd) Free energy diagrams- activation energy, exothermic, endothermic Metabolism- anabolic/catabolic ENZYMES Induced.

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Presentation on theme: "ENERGY Laws of Thermodynamics (1st/2nd) Free energy diagrams- activation energy, exothermic, endothermic Metabolism- anabolic/catabolic ENZYMES Induced."— Presentation transcript:

1 ENERGY Laws of Thermodynamics (1st/2nd) Free energy diagrams- activation energy, exothermic, endothermic Metabolism- anabolic/catabolic ENZYMES Induced fit model, lock & key Effect on activation energy Temperature, pH, Cofactors/Coenzymes, Enzyme/Substrate Concentration Inhibition, Allosteric Regulation Topics covered for the Quiz Friday

2 Time to sing

3 Feedback Inhibition Controlling Enzyme Function Cont’d

4 Enzymes Work Together Enzyme facilitates change of reactants  products then passed on to another enzyme Final desired product forms after series of reactions Processes are reversible and depend on the concentrations off substances available A B C D A forms B, now there is less A and B is used up for C, etc. Cycle starts pulling to the right, making more D E1E2E3 Overall force towards product D

5 When surrounding factors of the reaction are constant (pH, temperature), the enzyme production/activity is proportional to either the [Substrate] or the [Product ] FEEDBACK INHIBITION Enzyme regulation in which the formation of a product inhibits an earlier reaction in the sequence A B C D As the [D] increases, a signal is sent to E1 to say STOP ****When enough product is present, it turns itself off E1E2E3

6 Feedback Inhibition A way to self- regulate

7 How does a product inhibit an enzyme? Binds to the regulator site (inhibitor site) on enzyme near the beginning of the pathway Allosteric change- enzyme can’t bind onto its substrate All subsequent reactions are turned OFF -- the metabolic pathway is effectively halted

8 As end product is used up or removed ([product] decreased to a critical level), the inhibitor will fall off the first enzyme A B C D Reaction proceeds  the [product] is always controlled within a certain range E1E2E3 E1E2E3 The hallmark of all the reversible inhibitors is that when the inhibitor concentration drops, enzyme activity is regenerated

9 Allosteric regulation of the GLYCOLYTIC PATHWAY The oxidation of glucose providing energy in the cell Catabolic pathway- consumes glucose; produces ATP, NADH, and pyruvate Early reaction in the pathway catalyzed by phosphofructokinase-1 (PFK1)  Key step for the regulation of glycolysis When ATP levels rise, ATP binds an allosteric site in PFK1 to decrease the rate of the enzyme reaction; glycolysis is inhibited and ATP production falls *Negative feedback helping maintain a steady concentration of ATP in the cell Glucose (fructose-6-phosphate) PFK1 (fructose-1,6-bisphosphate) ATP NADH Pyruvate Figure: feedback inhibition in glycolysis Example of Feedback Inhibition in our Cells

10 hill.com/sites/ /student_view0/chapter6/feedb ack_inhibition_of_biochemical_pathways.html


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