Fermentation Processes and Types
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Questions and Answers

What primarily limits ATP yield during fermentation of pyruvate?

  • Excess oxygen reduction
  • Inability to convert pyruvate to Acetyl-CoA (correct)
  • NADH2 & FADH not further oxidized in ETC (correct)
  • High levels of substrate-level phosphorylation
  • Which type of fermentation only produces acid as the product?

  • Mixed-Acid fermenters
  • Acetogenic fermenters
  • Heterofermenters
  • Homofermenters (correct)
  • In anaerobic catabolism, what role does the organic compound serve?

  • Both electron donor and acceptor (correct)
  • Only as an electron acceptor
  • Neither an electron donor nor acceptor
  • Only as an electron donor
  • What is the main process responsible for energy generation in fermentation?

    <p>Substrate-level phosphorylation</p> Signup and view all the answers

    Which group of microorganisms is an example of heterofermenters?

    <p>Leuconostoc species</p> Signup and view all the answers

    What is produced from the decarboxylation of pyruvate in ethanol fermentation?

    <p>Acetaldehyde</p> Signup and view all the answers

    Which fermentative process yields acetic acid as a product?

    <p>Acetogenic Fermentation</p> Signup and view all the answers

    What is the primary substrate for acetogenic fermentation?

    <p>Glucose</p> Signup and view all the answers

    Which enzyme is responsible for converting pyruvate into acetyl-CoA?

    <p>Pyruvate decarboxylase</p> Signup and view all the answers

    In which type of fermentation do you primarily find enteric bacteria?

    <p>Mixed-Acid Fermentation</p> Signup and view all the answers

    During ethanolic fermentation, how many ATP molecules are produced?

    <p>2</p> Signup and view all the answers

    Which of the following is a characteristic of chemolithotrophic acetogens?

    <p>Utilize CO2 as a carbon source</p> Signup and view all the answers

    What are the products of mixed-acid fermentation?

    <p>Acetate, hydrogen ions, and ATP</p> Signup and view all the answers

    What is the first product generated from glucose during glycolysis?

    <p>2 Pyruvate</p> Signup and view all the answers

    Which enzyme is involved in the conversion of lactate to pyruvate?

    <p>Lactate dehydrogenase</p> Signup and view all the answers

    What is produced from alanine during the Stickland reaction?

    <p>Pyruvate</p> Signup and view all the answers

    What is the result of the reduction of glycine in the Stickland reaction?

    <p>Acetyl-P</p> Signup and view all the answers

    Which reaction involves substrate-level phosphorylation and yields ATP?

    <p>Conversion of 3 Pyruvate to Acetate</p> Signup and view all the answers

    What are the main products of the amino acid fermentation via the Stickland reaction?

    <p>3 Acetate, CO2, 3 NH4+, 3 ATP</p> Signup and view all the answers

    In the succinate-propionate pathway, what is formed from lactate first?

    <p>3 Pyruvate</p> Signup and view all the answers

    Which metabolic pathway yields Butyrate as a final product?

    <p>Amino acid fermentation</p> Signup and view all the answers

    At which wavelength does bacteriochlorophyll a primarily absorb light?

    <p>620 nm</p> Signup and view all the answers

    What role do phycobiliproteins play in cyanobacteria?

    <p>They assist in photosynthesis by transferring energy.</p> Signup and view all the answers

    How do phycobilisomes benefit cyanobacteria's growth in low light conditions?

    <p>They enhance light absorption efficiency.</p> Signup and view all the answers

    Which of the following light absorption features is characteristic of allophycocyanin?

    <p>Absorbs at wavelengths of 870, 805, 590, 360 nm</p> Signup and view all the answers

    In what organisms are chlorosomes primarily found?

    <p>Anoxygenic green sulfur and nonsulfur bacteria</p> Signup and view all the answers

    What is the efficiency of ATP production from glucose under standard conditions?

    <p>38.3%</p> Signup and view all the answers

    Which process uses light energy to reduce CO2 to organic compounds?

    <p>Photoautotrophy</p> Signup and view all the answers

    What is the role of carotenoids in photosynthesis?

    <p>They act as accessory pigments.</p> Signup and view all the answers

    Which of the following explains the significance of chlorophyll and bacteriochlorophyll in photosynthesis?

    <p>They capture and convert light energy.</p> Signup and view all the answers

    In the context of energy efficiency, what does Ereact represent?

    <p>Energy released as heat during a reaction.</p> Signup and view all the answers

    What products are generated from the conversion of succinate through the pathway ending in propionate?

    <p>2 Propionate, Acetate, CO2, H2O, 3 ATP</p> Signup and view all the answers

    What does the chlorophyll a structure contain that distinguishes it from cytochromes?

    <p>Mg cofactor</p> Signup and view all the answers

    Which reaction center is involved primarily in ATP synthesis?

    <p>Thylakoid membranes</p> Signup and view all the answers

    Which organism utilizes H2S as an electron donor in photosynthesis?

    <p>Purple bacteria</p> Signup and view all the answers

    What is the formula for calculating the efficiency of energy capture in ATP production?

    <p>(Ereact/EATP) * 100</p> Signup and view all the answers

    What are phycobiliproteins primarily associated with?

    <p>Light-harvesting in cyanobacteria</p> Signup and view all the answers

    What is the main light absorption property of blue phycobilin?

    <p>Absorbs strongly at 515 nm</p> Signup and view all the answers

    Which process is more energy-efficient: ethanolic-CO2 fermentation or lactate fermentation?

    <p>Lactate fermentation</p> Signup and view all the answers

    What type of phototroph does not utilize chlorophylls or bacteriochlorophylls freely?

    <p>Purple anoxygenic bacteria</p> Signup and view all the answers

    Study Notes

    Fermentation

    • Anaerobic catabolism
    • Organic compound serves as electron donor and acceptor
    • Substrate-level phosphorylation is the main energy production mechanism
    • No oxygen is involved - end products act as electron acceptors
    • Can occur in the presence or absence of oxygen

    Kinds of Fermentation

    • Lactate fermentation
    • Ethanol fermentation
    • Acetogenic fermentation
    • Mixed-acid and butanediol fermentation
    • Butyrate fermentation

    Ethanolic Fermentation

    • Substrate: hexose (glucose) or pyruvate
    • Glucose undergoes glycolysis to produce 2 pyruvate
    • 2 pyruvate decarboxylated to 2 acetaldehyde by pyruvate decarboxylase
    • 2 acetaldehyde reduced to 2 ethanol by alcohol dehydrogenase
    • Products: 2 ethanol, 2 CO2, 2 ATP

    Acetogenic Fermentation

    • Substrate: hexose (glucose) or pyruvate
    • Glucose undergoes glycolysis to produce 2 pyruvate
    • 2 pyruvate is converted to 2acetate, 2CO2 and 4H+
    • 2CO2 can be converted to 1 acetate
    • Products: 3 acetate, 3H+, 4 ATP

    Butanediol & Mixed-Acid Fermentation

    • Common to enteric bacteria and anaerobic Fungi

    Mixed-Acid Fermentation

    • Substrate: hexose (glucose) or pyruvate
    • Glucose undergoes glycolysis to produce 2 pyruvate
    • Pyruvate decarboxylated to Acetyl-CoA

    Butanediol Fermentation

    • Substrate: glucose or pyruvate
    • Glucose undergoes glycolysis to produce 2 pyruvate
    • Pyruvate decarboxylated to Acetyl-CoA
    • Acetyl-CoA converts to Acetoacetyl-CoA
    • Acetoacetyl-CoA reduced to B-Hydroxybutyryl-CoA
    • B-Hydroxybutyryl-CoA reduced to Butyryl-CoA
    • Butyryl-CoA converted to Butyrate
    • Products: Butyrate

    Butyrate Fermentation

    • Similar to mixed-acid fermentation
    • Starts with glucose undergoing glycolysis to produce 2 pyruvate
    • Products: Butyrate

    Amino Acid Fermentation

    • Also known as the Stickland reaction
    • Oxidation of one amino acid and reduction of another amino acid
    • Example: Alanine is oxidized (electron donor) and glycine is reduced (electron acceptor)
    • Starting material: Alanine and Glycine
    • Alanine oxidized to pyruvate
    • Glycine reduced to Acetyl-P
    • Pyruvate converts to Acetyl-P
    • Acetyl-P converted to Acetate
    • Products: 3 acetate, CO2, 3 NH4+, 3 ATP

    Propionate Fermentation

    • Also known as the succinate-propionate pathway
    • Lactate undergoes oxidation reactions
    • Starting material: 3 Lactate
    • 3 Lactate converted to 3 Pyruvate
    • 3 Pyruvate converted to acetate and succinate
    • Succinate converted to Propionate
    • Products: 2 propionate, acetate, CO2, H2O, 3 ATP

    Energy Efficiency

    • N=# of ATP formed
    • EATP= E in 1 high energy phosphoanhydride bond
    • Ereact= E released as heat in the chemical reaction (total free energy yield)
    • Efficiency = (EATP/Ereact)*100

    Photosynthesis

    • Autotrophs grow with CO2 as a carbon source
    • Photoautotrophy - light energy used to reduce CO2 to organic compounds
    • Photoheterotrophy - light energy used to reduce organic carbon to organic compounds
    • Generally, carbon reduction to cell material requires energy from ATP and electrons from NADH or NADPH
    • Anaerobic phototrophs are purple and green bacteria
    • Oxygenic phototrophs are algae and cyanobacteria

    Photosynthetic System Components

    • Light-harvesting molecules
    • Carotenoids
    • Phycobilins
    • Bacteriochlorophylls
    • Chlorophylls
    • Reaction centers

    Photosystems

    • Reaction centers are directly involved in ATP synthesis
    • Light harvesters - antenna pigments that funnel light energy to reaction centers

    Chromatophores or Lamellae

    • Membrane vesicle/membrane sac
    • House photosynthetic pigments
    • Found in purple bacteria

    Thylakoids

    • Resemble thylakoids in algae chloroplast
    • Found in cyanobacteria
    • House photosynthetic pigments

    Chlorophyll & Bacteriochlorophyll

    • Contain specific constituents on a tetrapyrrole ring and a hydrophobic alcohol
    • Chlorophyll a - absorbs red and blue light (green transmission)
    • Bacteriochlorophyll a - absorption depends on arrangement in membrane

    Accessory Pigments

    • Not required for photosynthesis
    • Carotenoids
      • Most widespread accessory pigment
      • Embedded in the membrane
      • Hydrophobic long chain of hydrocarbons
      • Photoprotective agents
    • Phycobilins
      • Main light harvesting systems in cyanobacteria
      • Responsible for red or blue-green linear tetrapyrroles - Assemble into "phycobilisomes" that attach to thylakoids

    Chlorosomes

    • Found in anoxygenic green S and non-sulfur bacteria
    • Houses bacteriochlorophylls

    Non-cyclic Photophosphorylation

    • Also known as the "Z" scheme
    • Electrons are excited by light energy and move through a series of carriers. This generates a proton gradient across the membrane, which is used to produce ATP.

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    Description

    Explore the fascinating world of fermentation in this quiz. Learn about anaerobic catabolism, types of fermentation like lactate and ethanolic fermentation, and the biochemical pathways involved. Ideal for students studying microbiology or biochemistry!

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