C atalysts Energy of Activation Most rea ctions do not start spontaneously They require energy such as a spark to get started This is called activation energy 2 Energy of Activation The ID: 904838
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Slide1
Enzymes:The Biological Catalysts
Slide2Energy of ActivationMost reactions do not start spontaneouslyThey require energy, such as a spark, to get started. This is called activation energy2
Slide3Energy of ActivationThe energy used to break the bonds in the reactants so they can be reformed in the products is called the energy of activation. 3
Slide4EnzymesEnzymes are biological catalysts that increase the reaction rate of biochemical reactions.4Characteristics of enzymes Made of proteins (or RNA).They are very specific and
only work with a certain
set of reactants or
substrates
that fit on their active site.
The enzyme shown is lysozyme
Slide5Induced FitEnzymes can be used over and over again. When an enzyme binds with the substrate, the bonded substrate interacts with the enzyme causing it to change shape. This change in shape facilitates the chemical reaction to occur. This is called the induced fit.5
Slide6Enzyme Example RibonucleaseRibonuclease decomposes RNA, and the nucleotides can be recycled. The purple part is the enzyme; the green part is the substrate (RNA). 6
Slide7Enzymes Work by Lowering the Energy of ActivationEnzymes increase the reaction rate by lowering the energy of activation. 7
Slide8The Enzyme Sucrase Decomposing Sucrose8
Slide9Initial VelocityThe reaction rate of an enzymatic reaction is always fastest at the beginning because plenty of substrate is available.9
Slide10Effects on Reaction Rates10Temperature increases enzyme action until the enzyme protein is denatured
Slide11Effect on Reaction Rates11Most enzymes work best with a pH of 7, but some can work in other ranges before denaturing
Slide12Effect onReaction Rates 12Competitive Inhibitors block enzyme activity by mimicking the substrate
Slide13Effect of Noncompetitive Inhibitors and Enzymatic Reaction Rates 13Noncompetitve inhibitors block enzyme function too, but attach a different point than the active site
Slide14Draw and Label Activation Energy Diagram14
Slide15Reactions to KnowHydrolysis Rxn – breaks apart a compound by adding a water moleculeDehydration Synthesis Rxn – links two compouunds by creating and releasing a water moleculeEndergonic Rxn – a reaction that requires energy Exergonic Rxn – a reaction that releases energyRedox Rxn – a reaction that involves transferring electrons15