Ch.5: Microbial Metabolism Flashcards Preview

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Flashcards in Ch.5: Microbial Metabolism Deck (32):
1

Metabolism

The sum of all chemical reactions in a cell

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Catabolism

  • the breakdown of complex organic compounds into simpler ones
  • are called catabolic or degradative reactions
  • Break bonds and release energy

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Anabolism

  • the building of complex organic molecules from simpler ones
  • called anabolic or biosynthetic reaction
  • Making bonds, energy is used/absorbed

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Diversity in prokaryotes are in their _______.

Chemistry (metabolism)

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Possible carbon sources for prokaryotes

  • Organic Carbon (hetero)
  • Inorganic Carbon (auto) ​in the form of CO2

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Possible energy sources for prokaryotes

  • Sunlight (photo)
  • Chemical compounds (chemo)
    • organic compounds (organo)
      • sugars, amino acids, etc.
    • inorganic chemical (litho)
      • H2, NH3, NO2-, Fe2+, H2S

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Photoautotroph

  • Energy: Sunlight (photo)
  • Carbon Source: Carbon Dioxide (auto)

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Photoheterotroph

  • Energy: Sunlight (photo)
  • Carbon Source: Organics (hetero)

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Chemolithoautotroph

  • Energy: Inorganic Chemicals (litho)
  • Carbon Source: Carbon Dioxide (auto)

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Chemoorganoheterotroph

  • Energy: Organic compounds  (organo)
  • Carbon Source: Organics (hetero)

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ATP

  • Energy currency of the cell
  • Adenine triphosphate
    • 3 phosphate groups
    • Ribose sugar
    • Adenine nitrogenous base

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​ATP Hydrolysis

  • Leads to ADP - Adenine diphosphate
    • Ribose 
    • Adenine nitrogenous base
    • 2 phosphate groups

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Most enzymes are large _____ molecules

Protein

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Location where the substrate binds to the enzyme

ACTIVE SITE

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When a molecule loses an electron, it is  ________

Oxidized

  • L.E.O
    • ​​Lose
    • Electron
    • Oxidized

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When a molecule gains an electron, it is _______

Reduced

  • G.E.R
    • ​​Gain
    • Electron
    • Reduced

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NAD+/FAD (vitamins)

  • Nicotinamide Adenine Dinucleotide & Flavin adenine dinucleotide
    • Oxidized forms
    • Electron Acceptors

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NADH/FADH2

  • Reduced forms
  • Electron donor

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​Aerobic Cellular Respiration

C6H12O6 O2 ------> CO2 H20 ATP

  • Terminal electron acceptor is O2
  • the product is water
  • Generates roughly 38 ATP (34 from ETC,  2 from glycolysis, 2 from Krebs Cycle)

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Steps to Aerobic Cellular Respiration

  1. Glycolysis
  2. Pyruvate Oxidation
  3. Kreb's Cycle/Citric Acid Cycle/ TCA Cycle
  4. Oxidative Phosphorylation (ETC/ATP Synthase)

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Metabolic Pathways

  • A sequence of chemical reactions in a cell
  • Determined by enzymes

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1). Glycolysis (anaerobic)

 

Investment Step

  • Glucose (6-carbon sugar) conversion to 2 Pyruvate (3-carbon sugar)

  • Inputs: 

    • 1 glucose

    • net 2 ADP

    • 2 NAD+

  • Outputs: 

    • net 2 ATP

    • 2 NADH

    • 2 Pyruvate

  • Occurs in cytoplasm  in both Euk/Pro

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Kinase

  • Enzyme that transfers phosphates
  • Hexokinase: glucose + ATP ----> glucose-6-phosphate + ADP
  • Pyruvate Kinase: PEP + ADP ---> ATP + Pyruvate

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Substrate Level Phosphorylation

moving a phosphate from a substrate directly to ADP to make ATP; requires an enzyme (kinase)

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2). Pyruvate Oxidation (anaerobic)

 

Transition Step

  • Used in aerobic and anaerobic respiration
  • generates 2 NADH and 2 Acetyl CoA
  • CoA = coenzyme A (small organic vitamin cofactor)
  • 2 CO2 is also made 
  • Eukaryotic
    • Mitochondria
  • Prokaryotic
    • Cytoplasm

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3). Krebs Cycle

 

  • Used in aerobic and anaerobic respiration
  • Generates 2 ATP, 6 NADH, 2 FADH2
    • ​​2 Cycles per glucose molecule
    • Lots of NADH generated
  • Release 4 CO2
  • Eukaryotic
    • Mitochondria
  • Prokaryotic
    • Cytoplasm

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4). Oxidative Phosphorylation (Electron Transport Chain/ATP Synthase/Chemiosmosis) 

 

 

Aerobic

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  • Series of molecules in a membrane that transports electrons
  • 1 NADH = 3 ATP -------- 10 NADH = 30 ATP
  • 1 FADH2 = 2 ATP -------- 2 FADH2 = 4 ATP 
  • 34 ATP made
  • oxygen (terminal electron acceptor)
  • A cell always has an ETC
    • allows flagella to rotate
    • also used for the transport of molecules
  • Eukaryotic
    • Inner membrane of  mitochondria
  • Prokaryotic
    • Across cytoplasmic membrane

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NADH Dehydrogenase

  • 1st protein enzyme of the ETC
  • catalyzes NADH ---> NAD+

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​Quinones

  • are hydrophobic non-protein molecules that accept both electrons and protons, but only pass on electrons

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​Proton Motive Force

  • Charge gradient/electrochemical gradient/proton gradient

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Anaerobic Respiration

  • Difference is the terminal electron acceptor
    • NO3- (nitrate) and SO4-2 (sulfate)
      • NO2- (nitrite) and H2S (hydrogen sulfide) are reduced forms of nitrate/sulfate
  • less ATP produced 

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Fermentation

 

 

  • Anaerobic Respiration
  • far less ATP made (2 ATP)
  • Pyruvate gets reduced
    • Pyruvate Reduction
      • produces alcohol and CO2
      • Acid compounds 
        • Depends on enzyme used
  • Terminal Electron acceptor is pyruvate

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