microbial metabolism supplemental instruction designed by pyeongsug kim ©2010...
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Microbial MetabolismMicrobial MetabolismSupplemental instruction
Designed by Pyeongsug Kim ©2010 [email protected]
Fall 2010
For Dr. Wright’s Bio 7/27 Class
Metabolism: try the practice questions. Also, we talked about aerobic respiration, anaerobic respiration, and fermentation. Compare and contrast them as follows:Which types of organisms (obligate aerobes, anaerobes, facultative anaerobes, aerotolerant organisms):
Utilize glycolysis (and which can’t)Utilize the Krebs cycle (and which can’t)Utilize an electron transport chain/oxidative phosphorylation (and which can’t)Can use a fermentation pathway (and which can’t)Which p[athway produces the most ATP? Which produces the least?Name an electron carrier used in each pathway (for one pathway, there is only one choice)
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MetabolismMetabolism: All body’s process that transform energy.
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Picture from http://www.eosremediation.com/support/bioremediation.html
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Microbial metabolismMicrobial metabolism -Chemical reaction used for biosynthetic and energy-harvesting process.-to live and reproduce. -Components of metabolic pathways• Energy sources ~ Sunlight, Organic or inorganic materials• Enzymes ~ Biological catalyst ~ to facilitate the pathways• ATP ~ The energy currency of a cell• Electron donor ~ e- from energy source• Electron carrier • Electron acceptor
• Catabolism
C A + B + energy Breaking down into smaller molecules; release energy.
Chemical reactions in Metabolism:Chemical reactions in Metabolism:• Anabolism
A + B + energy C Form larger molecules; require energy.
Reactants Product
Reactant Products
+ energy
+ energy
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Metabolic pathwayMetabolic pathway - A series of sequential chemical reactions. Initial compounds intermediates end products
- Linear, Branched, Cyclical(eg. TCA Cycle)
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_______-Biological catalysts speed up chemical reaction by … lowering activation energy -specific; proteins -sensitive to environmental conditions pH, Temperature,
For metabolic process, each chemical reaction in a metabolic pathway needs specific ________.
EnzymesEnzymes
enzyme
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Energy source or Electron donorEnergy source or Electron donor - The compounds that are oxidized to release ATP.
Picture from: http://i.telegraph.co.uk/telegraph/multimedia/archive/01031/news-graphics-2007_1031495a.jpg http://www.biojobblog.com/tags/microbes/
We inhale oxygen to generate ATP.
-________ -donated by the energy source. -transferred to another compound (electron carrier eg. NAD+, FAD2+).
Electrons
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Microorganisms oxidize carbohydrates(eg. glucose) as their primary source of energy.
EnergyEnergy(or electron)(or electron) Carriers Carriers - NAD+, NADP+, & FAD “Oxydized form”
- participate ultimately in ATP synthesis - When electrons are carried… NADH, NADPH, FADH2 “Reduced forms” or “Reducing power”
Terminal electron acceptorTerminal electron acceptor Aerobes – O2
Anaerobes – Inorganic molecules other than O2
Fermenters – Organic molecules
-___________ generate a proton motive force which can drive ATP synthesis-___________ used in Biosynthesis (eg. Pentose Phosphate Pathway, Photosynthesis)NADP+
NAD+, FAD
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Oxydized form
Reduced form
Electron carrierElectron
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Precursor metabolitesPrecursor metabolites - metabolic intermediates (links) in anabolic and catabolic pathway. e.g. pyruvates, Glucose 6-phosphate, Acetyl-CoA, …
- Used to generate ATP (catabolic) - Used to synthesize subunits of macromolecules (anabolic)
Picture from: http://i.telegraph.co.uk/telegraph/multimedia/archive/01031/news-graphics-2007_1031495a.jpg Designed by Pyeongsug Kim, ©2010 www.science-i.com
Picture from Dr.Wright Bio27 class slide
Three key metabolic pathways1) Glycolysis1) Glycolysis -produce pyruvates. -produce reducing power. -produce 6 precursor metabolites -2 ATPs are produced.
2) Krebs cycle(TCA Cycle)2) Krebs cycle(TCA Cycle) -require transition step(3carbons 2carbons)
= pyruvates(3C) acetyl-CoA(2C) -produce reducing power. -produce 2 precursor metabolites -2 ATPs are produced.
3) Respiration or ETC3) Respiration or ETC -oxydative phospholylation -Uses reducing power -Terminal electron acceptor(TEA) : oxygen, nitrate, carbon dioxide or other inorganic molecule, pyruvate regenerate electron carriers. (NADH NAD+, FADH2 FAD) -Lots of APTs!!!
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-Occur in _________________. -Glucose needs to be traped! Glucose 6-phosphate
1C6H12O6 2 ________ + 2 ____ + 2 _______
1glucose + 2NAD + 2ADP + 2Pi 2 pyruvates + 2NADH + (2H+)+ 2 ATP
- Oxygen required? (Yes / No)
GlycolysisGlycolysisCytoplasm(Cytosol)
*All cells undergo glycolysis!!!.
Pyruvates ATP NADH
- produce ____________. - NAD NADH (reduced / oxidized).
2 pyruvic acids
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-used in aerobic, anaerobic, & fermentation.
Pentose phosphate pathwayPentose phosphate pathway :alteranated glycolysis
- commonly used to make5-carbon sugars.
-NAPDH(reducing power) produced for biosynthesisbiosynthesis -Produce 2 precursors
• Mostly 5C-phosphate used synthesissynthesis of nucleotide (nucleic acids)
• 4C-phosphate used synthesissynthesis of amino acids
-But, no ATP
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In presence of oxygen - Pyruvic acids enter ___________ in eukaryotes. converted to __________ there. Kerbs Cycle(TCA)!
mitochondriaAcetyl-CoA
Copyright © The McGraw-Hill Companies, Inc.
After glycolysis…After glycolysis…
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Kerbs Cycle(TCA)Kerbs Cycle(TCA)-Aerobic, anaerobic respiration (but not fermentation)
-Circular pathway-Completes the oxidation of glucose-Produce…. Reducing power –NADH, FADH2
2 ATPs & 2 precursors.
Where does Kerbs Cycle(TCA) occur?
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•In Eukaryotic cell… Mitochondria
Citric acid cycle = Tricarboxylic acid(TCA) cycle =Krebs cycle
•In Prokaryotic cell… Cytoplasm
Krebs(TCA) cycleKrebs(TCA) cycle - aerobic respiration, anaerobic respiration - Convert pyruvate to acetyl-CoA - more ATPs than glycolysis - reducing powers: NADH, FADH2
Glycolysis and Krebs cycle In respiring cells.
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GlycolysisGlycolysis - in allall organisms. - aerobic respiration, anaerobic respiration, fermentation - produce pyruvates, ATPs. - reducing power: NADH
NADH, FADHNADH, FADH22 -RNA coenzyme (derived from Vitamin)- ________________-Used to temporarily store energy within the cell
*The more reduced = the more energy it holds.
NAD NADH (Reduced/Oxidized) : at Glycolysis, Krebs cycle NADH NAD (Reduced/Oxidized) : at ETC ( Electron Transport Chain )
electron carrier
Carried to ETC
Reduced coenzymes carry high-energy electronsto proton pumps where ATP is then made( ETC).
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RespirationRespiration-Oxydative phosphorylation or ETC-used reducing powers(NADH, FADH2) made in glycolysis and TCA.-ETC(electron transport chain) ~ proton motive force by proton pumps drive ATP synthase to produce ATP.
•Aerobic respirationAerobic respiration - oxygen as a TEA -aerobes, facultative anaerobes(under O2 presence)
-Most efficient at generating ATP
•Anaerobic respirationAnaerobic respiration - inorganic molecule (not O2) as a TEA : NO3
- (nitrate), (e.g., CO2, S, SO4-, NO3- or NO2-)-different electron carriers- Methanogens, sulfur bacteria, …
Eukaryotes -In inner mitochondrial membrane
Prokaryotes -In plasma membrane
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-Redox reactions; transfer electrons from an electron donor to an electron acceptor. -NADH, FADH2 (proton motive force) is used to synthesize ATP.
• In aerobic respiration Electron carriers ~ NADH, FADH2
Final electron acceptors ~ O2 (Oxygen!)
• In anerobic respiration Alternative electron carriers Final electron acceptors ~ inorganic molecules(not O2) NO3
- (nitrate), (e.g., CO2, S, SO4-, NO3
- or NO2-)
Electron transport chainsElectron transport chains(oxidative-phospholyration)(oxidative-phospholyration)
Cellular Cellular aerobic aerobic respiration (4 step)respiration (4 step)
Glycolysis (The transition step) Krebs cycle (Citric Acid Cycle)
The electron transport system
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Final electron acceptor - oxygen
Cellular Cellular anerobicanerobic respiration (4 step) respiration (4 step)
Glycolysis (The transition step) Krebs cycle (Citric Acid Cycle)
The electron transport system
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Final electron acceptor – inorganic molecule (not oxygen!)
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FermentationFermentation - Neither aerobic or anaerobic respiration - incomplete oxidation of a carbohydrate - Organic molecule(eg.pyruvate) as TEA!! as TEA!! - facultative anaerobes (under lack of O2 or inorganic molecule )
obligate fermenters (never use O2)
- use Glycolysis and additional step. - Only 2 ATPs - NO TCA(Krebs) Cycle! NO ETC!
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•Lactic Acid Fermenation - Food Spoilage - Food Production
Yogurt from Milk Pickles, Kimchi•Alcohol Fermentation -end product ~ alcohol,CO2
Alcoholic Beverages, Bread…
Obligate fermentersObligate fermenters - organic molecule as TEA - get their ATP from glycolysis - lactic acid bacteria, aerotolerants
Designed by Pyeongsug Kim, ©2009Picture from Dr.Wright Bio27 class slide, http://www.sciencedaily.com/releases/2006/10/061017091752.htm#
Different organisms can ferment different sugars. Commercially useful useful in identification
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Identification of fermenter - Different organisms can ferment different sugars.
Prokaryotes: whole process occurs in cytoplasm. Since don’t have organelles(mitochondria).
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Eukaryotes: Oxidative decarboxylation of pyruvate (pyruvate Acetyl-CoA)
is required in process of getting into the mitochondrion (where Krebs cycle occurs)
Picture from http://www.nslc.wustl.edu/courses/Bio2960/labs/04Microscopy/index.html
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Electron transport chainElectron transport chain-for aerobes; aerobic respiration. - Oxidative phosphorylation : NADH, FADH2 (proton motive force) is used to synthesize ATP.
Eukaryotes -In inner mitochondrial membrane
Prokaryotes -In plasma membrane
Aerobic respiration - terminal electron acceptor is ______.
( most / least) efficient at generating ATP -Obligate aerobes, Facultative anerobes(if O2 presence)
Anaerobic respiration - terminal electron acceptor is ____________ (e.g., CO2, S, SO4-, NO3- or NO2-, But Oxygen(O2))
( less / most ) efficient than aerobic respiration -Methanogens, sulfur bacteria, …
Fermentation - terminal electron acceptor _____________. (e.g. pyruvate)
- Do not use Krebs cycle (most / least) efficient at generating ATP -Facultative anerobes(if O2 absent) E.Coli
oxygen
inorganic molecule
organic molecule
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Aerobic respiration is the most efficient at generating ATP.
Fermentation is the least efficient at generating ATP.
Picture from Dr.Wright Bio27 class slide, http://www.thedailygreen.com/healthy-eating/eat-safe/xtreme-eating-awards-50060309
PhototrophsPhototrophs - Photosynthetic(Energy from sunlight)
- Produce sugars(glucose) consumed by chemoorganotrophs.
-Photosynthesis-Photosynthesis Chemical energy is used to reduce CO2 to sugar (CH2O) Carbon Fixation - recycling of carbon in the environment. - Oxygenic phototrophs Green Plants, Algae, Cyanobacteria
- Anoxygenic phototrophs Archaea, Green bacteria, Purple bacteria
-Primary producers
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LithotrophsLithotrophs -“Rock-Eaters” - Energy(Electron donor) source from inorganic molecules. H2, H2S, Fe2
+, NH4+
-Use CO2 for carbon (autotrophs) (usually) - Methanogens Lithotrophs(archaea) at hydrothermal vents Iron oxidizing bacteria some nitrogen fixers
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Picture from http://www.nature.com/nature/journal/v417/n6885/full/417137a.html
Picture from Dr.Wright Bio27 class slide, http://www.thedailygreen.com/healthy-eating/eat-safe/xtreme-eating-awards-50060309
Chemoorganotrophs(heterotrophs)Chemoorganotrophs(heterotrophs) - generate energy by degrading organic compounds. -Consumers, decomposers.
We are chemooranotrophs.We are eating organic compounds (made by phototrophs) to generate ATP.
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