Summary
Summary Microbial Metabolism (NWI-BB090)
- Course
- Institution
Summary of the lectures, lecture slides and tutorials of microbial metabolism with pictures.
[Show more]
Seller
Follow
lisavddries
Reviews received
Content preview
Microbial metabolism summaryL2 Bioenergetics
Metabolism = catabolism + anabolism
Anabolism = biosynthesis = make cell components with nutrients -> consumes energy
Catabolism = make energy carriers (ATP, NADH) (and waste) with energy sources
Energy source = chemical reaction, but which one
Electron donor = gets oxidised -> take away electron
Electron acceptor = gets reduced -> add electron
Thermodynamics: energy can’t be created or destroyed, only transformed
Exergonic = releases energy = dG < 0, make atp
Endergonic = uses energy = dG > 0, uses atp
Coupling of ender- and exogonic reactions
dG does not provide infromation on reaction rates!
Redox
Cations (+) are good electron acceptors, anions (-) are good electron donors
E0 = redox potential = tendency to donate/accept
E0 > 0 = electron acceptor, E0 < 0 = electron donor
E0 further away from 0 -> bigger potential
Difference between E0 of donor and acceptor = dG
Redox tower: ->
• High up: best donors
• Low: best acceptors
Reaction rate: dG + kinetics
Kinetics = velocity of catalysis
Reaction is sped up with catalysts (= enzyme)
• Not consumed in the reaction
• Lowers activation energy -> increases reaction rate
• Does not effect dG/equilibrium
,6 enzyme classes:
• Oxidoreductases = redox reactions
• Transferases = transfer of molecules
• Hydrolases = cleavage through hydrolysis
• Lyases = cleavage or build of bond without redox/hydrolysis
• Isomerases = isomerisation
• Ligases = bonding of molecules through ATP hydrolysis
Enzymes use cofactors: prosthetic groups or coenzymes
L3 chemoorganotrophy
Chemoorganotrophs = organisms that use organic molecules as energy source for catabolism
Can be aerobic: glycolysis -> citric acid cycle -> respiration
or anaerobic: glycolysis -> fermentation/anaerobic respiration
Glycolysis (anaerobe):
1. Preparation & production of gly-3p
2. Redox reactions -> NADH, ATP, pyruvate
3. Redox balance -> regenerate NAD, ADP (= respiration/fermentation)
Stage 1: 1 glucose split 2 gly-3p; uses 2 ATP
Stage 2: gly-3p oxidised to pyruvate; forms 4 ATP + 2 NADH
Formation of ATP: substrate level phosphorylation = uses free energy of oxidation reaction to
couple with ADP + P -> ATP + H2O
Electron carrier = transfers electrons; when recycled = reducing equivalents
NAD = electron acceptor
NADH = electron donor, E0 = -320 mV
NAD + e- -> NADH
Fermentation = anaerobic regeneration of NAD from NADH; stage 3 glycolysis
Named after end product: lactic acid fermentation forms lactate
Homofermentative lactic acid fermentation = produces only lactate
Heterofermentative lactic acid fermentation = produces lactate + ethanol + CO2
Entner-doudoroff (ED) pathway = missing aldolase -> no glycolysis -> glucose is oxidised and
decarboxylated first -> less ATP yield
Alcohol fermentation = produces only ethanol
+ other fermentation pathways
, L4 aerobic respiration
= aerobic stage 3 of glycolysis in chemoorganotrophs; yields ATP
= reoxidation of NADH with terminal electron acceptor (ex. O2 -> aerobic)
Uses proton motor force (PMF) for electron transport phosphorylation = chemiosmosis
PMF = oxidation of NADH is coupled to membrane and stores energy as H+ gradient
-> ATP with ATPsyntase = oxidative phosphorylation
1. Electron transport chain oxidises NADH -> reduces O2
2. H+ is pumped out of cell
3. ATP synthase uses PMF to generate ATP
Respiration builds up membrane potential with H+ = dP: electrical component + pH component
ATPsynthase: F0 = rotor; F1 = stable -> F0 rotates in F1 -> energy
Uses H+; ADP + P -> ATP
Electron transport chain:
• Complex I = NADH dehydrogenase + flavoproteins
• Complex II = succinate dehydrogenase + Q-cycling + flavoproteins
• Complex III = cytochrome bc complex
• Complex IV = cytochrome aa oxidase
• (Complex V = ATPsynthase)
Co-factors:
Flavoproteins = FAD/FADH & FMN/FMNH, can take up 2 e-
Q-cycling = have 2 groups that can take up e-, but only one at a time. Quinones + 2 e- -> quinols
Iron-sulphur proteins -> high redox potential
Cytochromes = protein that contain hemegroups: redox active iron
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller lisavddries. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $5.89. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
72042 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now