Test practice (Unit 3 & 4)
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Questions and Answers

What is the primary function of catabolism?

  • Breaking down larger molecules (correct)
  • Using light as an energy source
  • Building up biological molecules
  • Producing energy through photosynthesis

    • Heterotrophs can only use carbon dioxide as their source of carbon.

    False

    What do phototrophs use as their energy source?

    light

    Chemolithotrophs use ________ molecules as an energy source.

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

    Match the following types of organisms with their carbon source:

    <p>Autotrophs = Use carbon dioxide as sole carbon source Heterotrophs = Use organic compounds other than carbon dioxide Chemolithotrophs = Use inorganic molecules for energy Chemoorganotrophs = Use organic molecules for energy</p> Signup and view all the answers

    What is the process called that converts glucose into pyruvate?

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

    ATP is produced in the nucleus of the cell.

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

    What molecule serves as a precursor to ATP?

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

    The Krebs Cycle is also known as the __________.

    <p>Citric Acid Cycle</p> Signup and view all the answers

    Match the following molecules with their functions:

    <p>ATP = Energy molecule for metabolism ADP = Precursor to ATP cAMP = Signaling molecule Epinephrine = Hormone initiating glycogen breakdown</p> Signup and view all the answers

    Which metabolic process occurs in the presence of oxygen?

    <p>Krebs Cycle</p> Signup and view all the answers

    CyclicAMP acts as a second messenger in cellular signaling.

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

    During cellular respiration, what is added to ADP to form ATP?

    <p>Phosphate group</p> Signup and view all the answers

    Which of the following organisms are classified as photoautotrophs?

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

    Chemoheterotrophs use carbon dioxide as their sole source of carbon.

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

    List two essential nutrients required by microorganisms that cannot be synthesized.

    <p>Fatty acids and amino acids</p> Signup and view all the answers

    The main energy source for most microbes is in the form of ________.

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

    Match each nutrient with its use in microorganisms:

    <p>Carbon = Main energy source Nitrogen = Synthesis of proteins and nucleic acids Sulfur = Production of amino acids Phosphorus = Production of nucleic acids and phospholipids</p> Signup and view all the answers

    Which of the following elements is NOT considered a trace element needed by microorganisms?

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

    Photoheterotrophs are common in most ecosystems.

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

    What is the primary role of vitamins in microbial metabolism?

    <p>Co-enzymes</p> Signup and view all the answers

    Which of the following organisms converts pyruvate to lactic acid?

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

    Humans only convert pyruvate to lactic acid during rest periods.

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

    What is a common product of fermentation in yeast?

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

    Enterobacter uses fermentation to produce _____ as one of its products.

    <p>2,3-butanediol</p> Signup and view all the answers

    Match each fermentation type with its main product:

    <p>Lactic Acid Fermentation = Lactic Acid Alcohol Fermentation = Ethanol 2,3-Butanediol Fermentation = 2,3-Butanediol Mixed Acid Fermentation = Mixed Acids</p> Signup and view all the answers

    Which of the following is NOT a product of the Krebs cycle?

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

    Deamination involves the addition of an amine group to an amino acid.

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

    What role do NADH and FADH2 play in the electron transport chain?

    <p>They act as electron carriers.</p> Signup and view all the answers

    Bacteria can convert ammonia to _____ and use that in the TCA cycle.

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

    Match the following metabolic processes with their descriptions:

    <p>Krebs Cycle = Produces ATP, NADH, and FADH2 Deamination = Removal of the amine group from amino acids Fermentation = Anaerobic process generating minimal energy Electron Transport Chain = Uses NADH and FADH2 to create a proton gradient</p> Signup and view all the answers

    What is generated in fermentation that allows continued metabolic processes?

    <p>Electron acceptors and carriers</p> Signup and view all the answers

    Fatty acids enter the Krebs cycle directly.

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

    What is the primary energy molecule produced at the end of the electron transport chain?

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

    Which phase of bacterial growth is characterized by little or no cell division?

    <p>Lag Phase</p> Signup and view all the answers

    Synchronous growth means that all cells in the culture divide at different times.

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

    What happens during the stationary phase of bacterial growth?

    <p>The number of new cells produced equals the number of cells dying.</p> Signup and view all the answers

    During the _____ phase, cells begin to die due to lack of nutrition.

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

    What occurs during the log phase of bacterial growth?

    <p>Cells divide rapidly and population grows exponentially.</p> Signup and view all the answers

    Match each phase of the bacterial growth curve with its description:

    <p>Lag Phase = Little or no cell division; metabolically active Log Phase = Rapid division with nutrient consumption Stationary Phase = Number of new cells equals number dying Death Phase = Decline in population due to lack of nutrition</p> Signup and view all the answers

    During the log phase, the growth rate of bacteria slows down due to decreasing nutrients.

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

    What characterizes the log phase in terms of cell division?

    <p>Increased cell division and rapid population growth.</p> Signup and view all the answers

    Which type of microbe prefers acidic conditions?

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

    All bacteria grow synchronously during their life cycle.

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

    What is the growth pattern of an obligate anaerobe?

    <p>Cannot grow in the presence of oxygen.</p> Signup and view all the answers

    Barophiles thrive at high __________ pressure.

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

    Match the following microorganisms to their preferred temperature range:

    <p>Thermophiles = 50 – 60 C (Max 113 C) Mesophiles = 20 – 40 C (Max 45 C) Psychrophiles = 10 – 20 C (Max 30 C)</p> Signup and view all the answers

    Which type of microbe can metabolize both aerobically and anaerobically?

    <p>Facultative anaerobe</p> Signup and view all the answers

    Halophiles can survive in low osmotic pressures.

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

    What is the optimal pH range for Neutrophiles?

    <p>pH 5.4 – 8.0</p> Signup and view all the answers

    Study Notes

    Metabolism

    • All chemical reactions that occur in a living organism.
    • Catabolism: breaking down molecules.
    • Anabolism: building up molecules.
    • Examples include: production of biological molecules, cellular respiration, digestion, and muscle contraction.

    Microbial Carbon Sources

    • Autotrophs: use carbon dioxide as their sole carbon source.
      • Examples: Plants, algae, cyanobacteria
    • Heterotrophs: use organic compounds other than carbon dioxide as a carbon source.
      • Examples: Humans, fungi, animals, and protozoans.
      • Most microorganisms are chemoheterotrophs, using nutrients obtained from hosts.

    Microbial Energy Sources

    • Phototrophs: use light as an energy source.
      • Energy is produced through photosynthesis.
    • Chemotrophs: use organic or inorganic molecules as an energy source.
      • Chemolithotrophs: use inorganic molecules for energy.
      • Chemoorganotrophs: use organic molecules for energy.

    Combining Carbon and Energy Sources

    • Photoautotrophs: use light for energy and carbon dioxide for carbon.
      • Example: Plants
    • Photoheterotrophs: use light for energy and organic molecules for carbon.
      • Rare form of metabolism.
    • Chemoautotrophs: use chemicals for energy and carbon dioxide for carbon.
      • Rare form of metabolism.
    • Chemoheterotrophs: use chemicals for energy and other organic molecules for carbon.
      • Most organisms (except plants).

    Microbial Nutritional Requirements

    • Microorganisms require carbon, nitrogen, sulfur, phosphorus, and vitamins.
    • They also need sodium, potassium, chlorine, magnesium, calcium, iron, and iodine.
    • Continual intake of essential nutrients that cannot be synthesized is required.
      • Examples: fatty acids and amino acids.
    • These nutrients make up the essential macromolecules of life:
      • Carbohydrates, amino acids, lipids, proteins, and DNA/RNA.

    Microbial Growth Factors

    • Carbon compounds are the main energy source for most microbes.
      • Usually in the form of carbohydrates.
    • Nitrogen is used to synthesize:
      • Enzymes, proteins, and nucleic acids.
    • Sulfur is used to produce amino acids and coenzymes.
    • Phosphorus is used for nucleic acids and phospholipids.
    • Trace elements (Cu, Zn, Co, Fe, Mn, Se) are used with enzymes as co-factors.
    • Vitamins are used as co-enzymes.
    • Amino acids, purines, and pyrimidines are also required.

    Metabolism and Microbial Enzymes

    • The number and type of enzymes an organism has determines its nutritional requirements.
    • Microorganisms with fewer enzymes need more nutrients because they cannot synthesize needed substances.

    Catabolic Reactions

    • Result in the breakdown of molecules and the release of smaller molecules and energy.
      • Examples:
        • 2 H2O(g) 🡪 2 H2(g) + O2(g)
        • NaCl(s) 🡪 Na(s) + Cl2(g)
        • 6O2 + C6H12O6 → 6CO2 + 6H2O + energy

    Microbial Metabolism: Adenosine Triphosphate (ATP)

    • The energy molecule used by cells.
    • Produced in the mitochondria.
    • Provides energy for:
      • Movement, such as muscle contractions.
      • Movement of chromosomes during cell division.
      • Active transport.
      • Production of proteins, enzymes, and hormones.

    Microbial Metabolism: Adenosine Diphosphate (ADP)

    • Precursor to ATP.
    • Lower energy compound.
    • A phosphate group is added to ADP during cellular respiration, creating a high energy bond.
    • When energy is needed, this phosphate group can be removed releasing energy.

    Microbial Metabolism: Cyclic AMP (cAMP)

    • A molecule made from ATP that is a common signaling molecule found inside cells.
    • Integral part of reaction sequences.
    • Relays messages from outside the cell, initiating metabolic activity inside the cell.
    • Example: Epinephrine uses cAMP to initiate glycogen breakdown.

    Glycolysis

    • All living cells can convert glucose into pyruvate.
    • Called glycolysis.
    • Takes place in the cytoplasm.
    • Bacteria can convert specific sugars into pyruvate using the glycolytic pathway:
      • Mannitol, glucose, lactose, and sucrose.
    • This forms the basis for tests to identify bacteria.
    • The end result of each catabolic process is the production of pyruvate.

    Krebs Cycle (Citric Acid Cycle, Tricarboxylic Acid Cycle)

    • Occurs after glycolysis.
    • In the presence of oxygen, pyruvate is changed to Acetyl-CoA, which then enters the Krebs cycle.
    • Occurs in the cytoplasm.
    • Products: ATP, carbon dioxide gas, NADH, and FADH2.

    Electron Transport Chain (ETC)

    • Series of proteins located in the membrane of the cell.
    • These proteins accept electrons from NADH and FADH2 and pump H+ ions outside the membrane, creating an electrochemical (charge) gradient.
    • H+ ions flow back across the membrane through ATP synthase.
    • As ions pass through the pump, Pi is added to ADP to create ATP.

    Protein Metabolism

    • Bacteria can use proteins and fatty acids for energy.
    • Proteins can be converted to pyruvate and then cycled into the Krebs cycle.
    • Intermediaries are produced from amino acids.
      • Example: Acetyl-CoA
    • Deamination must occur to use proteins.
      • Removing the amine group from the amino acid.
      • Ammonia is produced and excreted.
      • Some bacteria convert ammonia to urea, which is used as an entry point into the TCA cycle.

    Fats and Lipids Metabolism

    • Bacteria can cycle fats into the TCA cycle.
    • Fats decompose into glycerol and fatty acids.
    • Glycerol is converted to pyruvate and then enters as Acetyl-CoA.
    • Fatty acids enter the Krebs cycle directly.

    Fermentation

    • A low-energy anaerobic metabolic process.
    • Very little energy is created.
    • Electron acceptors and carriers are generated so metabolic processes can continue.
    • Some bacteria reduce pyruvate to produce energy through fermentation:
      • Lactic acid fermentation.
      • Alcohol fermentation.
      • 2,3-Butanediol fermentation.
      • Mixed acid fermentation.

    Fermentation and Enzyme Types

    • The type of fermentation depends on the types of enzymes the organisms make.
      • Lactobacillus converts pyruvate to lactic acid.
        • Lactic acid is sour and has industrial applications.
      • Humans convert pyruvate to lactic acid in muscles.
      • Saccharomyces cerevisiae (fungus) makes alcohol through fermentation.
      • Enterobacter uses fermentation to produce 2,3-butanediol.
      • Escherichia coli produces mixed acids.
    • All of these processes yield a small amount of ATP.

    Overall Metabolism Summary

    • Carbohydrates, fats, and proteins can all be used for energy.
    • They are broken down into Acetyl-CoA and then enter the Krebs cycle.
    • NADH and FADH2 carry electrons to the electron transport chain.
    • The electron transport chain uses this energy to produce ATP (34 ATP molecules).
    • Glycolysis and the Krebs cycle produce a smaller quantity of ATP on their own (2 ATP for each).
    • Fermentation occurs when oxygen is not present, and produces very little ATP.

    Microbial Reproduction

    • Microbes reproduce primarily through binary fission, a process where a single cell divides into two identical daughter cells.
    • Some microbes, like yeasts, use budding to produce offspring. Budding involves the formation of a small outgrowth or bud from the parent cell, which eventually detaches to become a new individual.

    Factors Affecting Microbial Growth Rate

    • pH:
      • Acidophiles thrive in acidic environments (pH 1.0 - 5.4).
      • Neutrophiles prefer neutral conditions (pH 5.4 - 8.0).
      • Alkaliphiles flourish in basic conditions (pH 7.0 - 11.5).
    • Temperature:
      • Thermophiles grow optimally at high temperatures (50 - 60°C, maximum 113°C).
      • Mesophiles prefer moderate temperatures (20 - 40°C, maximum 45°C).
      • Psychrophiles thrive in low temperatures (10 - 20°C, maximum 30°C).
    • Osmotic Pressure:
      • Organisms require an optimal level of solutes to survive.
      • Halophiles can withstand high osmotic pressures (hypertonic conditions).
    • Moisture:
      • Most microbes require some level of moisture to survive and grow.
      • Some microbes can form spores (dormant forms) to survive in harsh conditions, including dryness.
    • Barometric Pressure:
      • Barophiles are organisms that thrive under high barometric pressure.
    • Oxygen Requirements:
      • Obligate Aerobes: Require oxygen for growth and cannot survive without it.
      • Obligate Anaerobes: Poisoned by oxygen, rely on anaerobic metabolism for energy.
      • Facultative Anaerobes: Can grow with or without oxygen, but aerobic metabolism is more efficient.
      • Microaerophiles: Need lower concentrations of oxygen for growth, high levels are toxic.
      • Aerotolerant Anaerobes: Do not utilize oxygen but are not harmed by it.

    Bacterial Growth

    • Colonies are assumed to originate from a single bacterial cell.
    • Cells undergo repeated binary fission, leading to colony formation.
    • All cells within a colony are genetically identical, originating from a single ancestral cell.
    • Bacterial growth within colonies is non-synchronous.

    Synchronous vs. Non-Synchronous Growth

    • During logarithmic growth phase:
      • Synchronous growth: All cells divide simultaneously.
      • Non-synchronous growth: Cells divide at varying times within the generation time (more realistic).

    The Bacterial Growth Curve

    • Bacterial populations exhibit predictable growth phases:
      • Lag Phase: Slow or no growth, cells metabolically adjust to the new environment.
      • Log Phase: Rapid growth, cells divide at a constant rate (generation time).
      • Stationary Phase: Growth rate slows, new cell production balances cell death due to nutrient depletion and waste accumulation.
      • Death Phase: Cell death surpasses new cell production, environment becomes unfavorable for growth.

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    Description

    This quiz covers essential concepts in microbial metabolism, including catabolism and anabolism. It explains the different carbon and energy sources used by organisms, such as autotrophs and heterotrophs, as well as phototrophs and chemotrophs. Test your understanding of how these processes contribute to life.

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