Mdule 3 Chapter 5 Micrbial Metablism Catablic and Anablic Reactins Metablism Tw general types f metablic reactins: : : Recall frm Chapter 2: Energy can be when bnds Energy can be when bnds Catablism Purpse is t Anablism Requires t frm bnds Purpse is t Catablic reactins are cupled with anablic reactins Cupled by A metablic pathway is a f chemical in a cell Metablic reactins are cntrlled by prteins Enzymes Enzymes are bilgical catalysts fr a chemical reactin Specificity is due t f enzyme Prteins (enzymes) have characteristic Structure is fr If enzyme, enzyme desn t Enzymes act n ne r mre bind at
Each enzyme is specific Names f enzymes end in Sucrase, catalase, DNA plymerase Enzyme cmpnents Many enzymes are made entirely f Sme cnsist f 2 cmpnents Apprtein: Cfactr: : rganic cfactr Hlenzyme: Enzyme Mechanism The general sequence f events in an enzymatic reactin Substrate(s) binds t This is called The substrate(s) is transfrmed Transfrmed mlecule(s), the, released frm enzyme N lnger Enzyme nly t Enzyme is free t Sequence cntinues until enzyme is, r enzyme Factrs influencing enzymatic activity Enzymes require t functin Hstile envirnments can cause prteins t Temperature In general, chemical reactins speed up as temp Fr enzymes, t temperature causes ph ph is All enzymes have ph frm preferred ph will Inhibitrs Certain chemicals that bind t enzymes Tw classes f inhibitrs: Cmpetitive inhibitrs bind with substrate fr the f the enzyme drugs inhibit (an essential ) synthesis via cmpetitive inhibitin drugs were the first effective antibacterial drugs Nncmpetitive inhibitrs bind Aka inhibitin prevents replicatin f HIV via nncmpetitive inhibitin
Feedback inhibitin Cntrl f enzymatic activity by use f Energy Prductin Energy is stred in Recall, cvalent bnds frm by Energy is stred in cvalent bnds Catablism invlves stripping high energy frm mlecules and cncentrate them in the bnds f ATP Reactins that invlve remving and adding electrns are called reactins Oxidatin-Reductin reactins Oxidatin: Reductin: reactin: an xidatin reactin with a reactin Catablism is the f highly mlecules The Generatin f ATP Energy released by redx reactins trapped by is generated by the f Additin f a Requires energy 3 types f t generate Substrate-level phsphrylatin f a PO4- t generates prcess and Oxidative phsphrylatin frm rganic mlecule ( ) used t generate ( ) gradient Gradient used t prductin Phtphsphrylatin Occurs nly in cells transfers energy t electrns get excited Excited used t generate gradient, drive prductin Similar t phsphrylatin, using instead f t build dam Metablic pathways f energy prductin Catablism invlves series f cntrlled reactins Releasing energy in ne reactin generates t much heat Energy cannt be harnessed efficiently Catablism invlves a series f reactins extracted t Sequence f reactins called a
Every reactin in a pathway is perfrmed by Carbhydrate catablism Carbhydrates are f energy is mst cmmn energy surce Glucse is brken dwn via tw general prcesses: Cellular respiratin Fermentatin Cellular Respiratin (catablism) f glucse Waste prducts are Mst f the is prduced via phsphrylatin Tw types f respiratin Respiratin with Respiratin withut Multiple pathways invlved Glyclysis The f glucse mlecule (6 Carbns) t 2 pyruvic acid mlecules (3 C) Main end-prducts 2 2 2 via Electrn Carriers (empty electrn carrier) remves electrns frm ( ) Becmes (full electrn carrier) takes electrns t their final destinatin The pathway Requires 2 t get started is t Overall prduced by glyclysis Glyclysis require xygen Alternatives t glyclysis Pentse-phsphate pathway Uses and ( ) Operates with glyclysis Entner-Dudrff pathway Prduces and Des glyclysis Intermediate Step Pyruvic acid (frm ) is and is prduced waste
The Krebs Cycle Aka r citric acid cycle A series f 8 reactin steps Cmpletely catablizes rganic mlecule t Main prducts are,, 1 ATP carriers Final end-prduct is same as starting reactant; a cycle The pathway enters Krebs cycle Generates 1 ATP prduced by generated as waste The Electrn Transprt Chain A series f pass electrns t ETC Becme Return t glyclysis, Krebs cycle Energy released frm used t drive frm inside cell t cell Prduced cncentratin gradient Electrns end up n - ETC generates gradient gradient favrs int cell diffuse acrss membrane freely re-enters cell via Thrugh transprter called captures energy in gradient Prduces à Summary f Respiratin Aerbic respiratin: the final electrn acceptr in ETC is Organism is an Oxygen is cnverted t à Anaerbic respiratin: the in the ETC is Usually an Yields than aerbic respiratin because nly part f the Krebs cycle perates under cnditins surces can be used Eg, can xidize lipids, Plymers brken dwn by enzymes Smaller subunits enter catablism at varius pints f glyclysis, Krebs cycle Fermentatin Scientific definitin: Releases energy frm f mlecules (fd) Des xygen
Des nt use the Uses an as the final electrn acceptr ATP generated nly via cnverted int rganic mlecule end-prduct à Main purpse is t regenerate (frm ) fr can participate in again Prduces f energy - left in end-prduct The Pathway prduces glucse during glyclysis prduced during glyclysis pyruvic acid; regenerates Lactic Acid fermentatin prduces Ethanl fermentatin prduces Chemtherapy à highly txic Inhibit Cytchrme c Oxidase, enzyme in ETC Cell cannt Cell cannt Cell nt affected by cyanide Phtsynthesis Pht: cnversin f energy int energy ( ) -dependent (light) reactins Synthesis: Carbn : fixing carbn int mlecules Light energy is absrbed by In f chlrplasts in eukarytes In f prkarytes Light energizes r in Excited electrns are passed n t ATP is generated Occurs in tw ways: ( ) ( ) Cyclic phtphsphrylatin electrns passed n t ATP generated by Electrns Nncyclic phtphsphrylatin electrns passed n t
ATP generated by Electrns placed n à frms Electrns in chlrphyll replaced by electrns frm à prduced as waste Light-independent (Dark) reactins Aka The cycle Uses ATP, NADPH prduced by nncyclic phtphsphrylatin t frm Prcess requires lts f prduced Metablic diversity amng rganisms Organisms classified accrding t Specifically, lk at basic requirements t sustain life Tw classificatins based n surces Phttrphs Chemtrphs Tw classificatins based n surces Auttrphs Aka Hetertrphs Aka Classificatin can be cmbined Phtauttrph Phthetertrph Chemauttrphs Chemhetertrphs Chemhetertrphs Hetertrphs classified accrding t their surce f rganic mlecule Saprphytes Parasites Metablic diversity f great interest Can cause prblems, prvide ptential slutins Rubber degrading bacteria can destry gaskets in machinery BUT, can be used t degrade discarded tires Rhdcccus erythrplis can cause disease in humans, animals BUT, can remve sulfur frm petrleum