Enzymes_and_Signaling - Metabolism & Enzymes...

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Unformatted text preview: Metabolism & Enzymes From food webs to the life of a cell energy energy energy Flow of energy through life Life is built on chemical reactions transforming energy from one form to another organic molecules ATP & organic molecules organic molecules ATP & organic molecules sun solar energy ATP & organic molecules Metabolism Chemical reactions of life forming bonds between molecules dehydration synthesis synthesis anabolic reactions breaking bonds between molecules hydrolysis digestion catabolic reactions Thats why theyre called anabolic steroids ! Examples dehydration synthesis (synthesis) hydrolysis (digestion) + + 2 enzyme enzyme Examples dehydration synthesis (synthesis) hydrolysis (digestion) enzyme enzyme Chemical reactions & energy Some chemical reactions release energy exergonic digesting polymers hydrolysis = catabolism Some chemical reactions require input of energy endergonic building polymers dehydration synthesis = anabolism digesting molecules= less organization= lower energy state building molecules= more organization= higher energy state Endergonic vs. exergonic reactions exergonic endergonic- energy released- digestion- energy invested- synthesis- G G = change in free energy = ability to do work + G Energy & life Organisms require energy to live where does that energy come from? coupling exergonic reactions (releasing energy) with endergonic reactions (needing energy) + + energy + energy + What drives reactions? If reactions are downhill, why dont they just happen spontaneously? because covalent bonds are stable bonds Stable polymers dont spontaneously digest into their monomers Activation energy Breaking down large molecules requires an initial input of energy activation energy large biomolecules are stable must absorb energy to break bonds energy cellulose CO 2 + H 2 O + heat Too much activation energy for life The amount of energy needed to destabilize the bonds of a molecule moves the reaction over an energy hill Not a match ! Thats too much energy to expose living cells to ! Reducing Activation energy Catalysts reducing the amount of energy to start a reaction Pheeew that takes a lot less energy ! Catalysts So whats a cell got to do to reduce activation energy? get help! chemical help ENZYMES G Call in the ENZYMES ! Think first (dont just blurt out the answer) Now, check with your neighbor True or False: Enzymes provide the activation energy necessary to get chemical reactions started Explain. Enzymes Biological catalysts proteins ( & RNA ) facilitate chemical reactions increase rate of reaction without being consumed reduce activation energy dont change free energy ( G ) released or required required for most biological reactions highly specific thousands of different enzymes in cells control reactions of life Enzymes vocabulary...
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Enzymes_and_Signaling - Metabolism & Enzymes...

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