Biochemistry: Cellular Respiration and Metabolism
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Questions and Answers

What is the primary function of transaminases in amino acid biosynthesis?

  • To transport amino acids across membranes
  • To synthesize glucose from amino acids
  • To remove amino groups from amino acids
  • To move amino groups between molecules (correct)
  • In which type of medium are the exact nutrient compositions known?

  • Complex medium
  • Defined medium (correct)
  • Differential medium
  • Selective medium
  • Why are animal pathogens often cultured in complex media?

  • They do not utilize simple carbon sources
  • They grow better in solid media than in liquid media
  • They require specific purified chemicals for growth
  • They have minimal biosynthetic capacity and need numerous nutrients (correct)
  • What is the role of ACP in fatty acid biosynthesis?

    <p>To serve as a carrier for building fatty acids</p> Signup and view all the answers

    What does selective media do?

    <p>Inhibits the growth of certain organisms while allowing others to thrive</p> Signup and view all the answers

    During binary fission, how is cell division characterized?

    <p>It leads to replication of DNA before division</p> Signup and view all the answers

    What characteristic is associated with liquid media?

    <p>Facilitates rapid and constant mixing for uniform conditions</p> Signup and view all the answers

    What is one advantage of using solid media for microbial growth?

    <p>It facilitates the counting of colony forming units (CFU)</p> Signup and view all the answers

    What is the primary product of glycolysis?

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

    What happens to NADH produced during glycolysis?

    <p>It is recycled through fermentation or respiration.</p> Signup and view all the answers

    In aerobic conditions, how much ATP is generated from one glucose molecule?

    <p>36-38 ATP</p> Signup and view all the answers

    Which molecule serves as the terminal electron acceptor in aerobic respiration?

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

    What is produced during fermentation under anaerobic conditions?

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

    What is the role of ATP Synthase in cells?

    <p>To synthesize ATP using energy from proton movement</p> Signup and view all the answers

    Which of the following does NOT occur during glycolysis?

    <p>Formation of six carbon dioxide</p> Signup and view all the answers

    What mechanism allows cells that do not require oxygen to generate a proton motor force?

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

    What is the role of the divisome during cytokinesis?

    <p>It facilitates the formation of the septum.</p> Signup and view all the answers

    Which of the following is a disadvantage of direct count using a Petroff-Hausser counting chamber?

    <p>It cannot differentiate between live and dead cells.</p> Signup and view all the answers

    What is the statistical significance range for counting colonies on a plate?

    <p>30-300 colonies</p> Signup and view all the answers

    What does TMTC stand for in the context of colony counting?

    <p>Too Many To Count</p> Signup and view all the answers

    Which method allows for counting in lower concentrations of cells?

    <p>Viable Count</p> Signup and view all the answers

    What is a primary feature of the pour plate method?

    <p>It involves mixing the sample with agar before solidifying.</p> Signup and view all the answers

    Which of the following statements about cytokinesis is incorrect?

    <p>It does not involve the cell wall synthesis.</p> Signup and view all the answers

    What is the calculated concentration of bacteria if 159 colonies are counted from a total dilution of $10^{-3}$?

    <p>1.59 x $10^{6}$ CFU/mL</p> Signup and view all the answers

    How many cells will there be after 60 minutes if the initial population (N0) is 2 cells and the generation time (g) is 20 minutes?

    <p>16 cells</p> Signup and view all the answers

    In which phase does microbial growth occur at its maximum rate due to an abundance of nutrients?

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

    What method allows for continuous growth of cultures while mimicking low nutrient environments?

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

    What is the maximum temperature range for mesophiles?

    <p>15°C - 45°C</p> Signup and view all the answers

    Which type of organism can grow optimally at temperatures exceeding 80°C?

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

    Which group of microorganisms can grow in environments with salt concentrations below 1%?

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

    What pH range do neutrophiles thrive in?

    <p>Between pH 6-8</p> Signup and view all the answers

    What happens to bacterial growth when there is too little fresh media in a continuous culture?

    <p>Bacteria enters stationary or death phase</p> Signup and view all the answers

    What is the function of buffers in artificial mediums?

    <p>To maintain a constant pH</p> Signup and view all the answers

    Which of the following characteristics is typical of acidophiles?

    <p>Growth below pH 5</p> Signup and view all the answers

    What is the primary function of the bacterial cell wall?

    <p>To protect cells from osmotic pressure</p> Signup and view all the answers

    Which component is not involved in the synthesis of peptidoglycan?

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

    Which characteristic is unique to Gram-negative bacteria compared to Gram-positive bacteria?

    <p>Presence of two membranes</p> Signup and view all the answers

    What energy sources drive the active transport system for large proteins across the membrane?

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

    Which structure is specifically referred to as the peptidoglycan layer?

    <p>Cell wall</p> Signup and view all the answers

    What role do Penicillin-Binding Proteins (PBPs) play in bacterial cell wall synthesis?

    <p>Catalyzes glycosyl transferase and transpeptidase activities</p> Signup and view all the answers

    What links the peptide side chains in the peptidoglycan layer of Gram-negative bacteria?

    <p>Direct cross-linking</p> Signup and view all the answers

    In the context of microbial cell structure, the term 'cell envelope' encompasses which of the following?

    <p>All layers surrounding the cell including membranes</p> Signup and view all the answers

    Study Notes

    Glycolysis Pathway

    • Glucose is broken down in a catabolic pathway that does not require oxygen
    • 2 ATP are produced from substrate phosphorylation
    • Glucose is converted to pyruvate, NADH is produced

    Recycling Reduced Coenzymes: Fermentation

    • Fermentation occurs in the absence of oxygen
    • Fermentation recycles reduced coenzymes: NADH
    • This process produces ethanol and lactate

    Recycling Reduced Coenzymes: Respiration

    • Respiration requires oxygen.
    • 2 Pyruvate are converted using cofactors to produce carbon dioxide, NADH, FADH, and GTP
    • The Citric Acid/Krebs/TCA cycle is part of respiration

    Electron Transport Chain (ETC)

    • Oxidizes electron carriers NADH and FADH2
    • Protons are pumped across the membrane generating a proton motor force
    • Oxygen acts as the terminal electron acceptor

    ATP Synthase

    • ATP is synthesized by the movement of protons down the gradient
    • This enzyme is called ATP Synthase
    • ATP Synthase is reversible

    Anabolic Metabolism

    • Organisms can synthesize sugars, polysaccharides, amino acids, proteins, nucleotides, nucleic acids, fatty acids, and lipids
    • Gluconeogenesis produces glucose when it is not available
    • Transaminases move amino groups between molecules
    • ACP is a carrier for fatty acids

    Microbial Division and Growth

    • Culture media is used to grow microbes

    Defined Medium

    • Contains minimum nutrients for growth and is made with purified chemicals
    • The exact composition is known
    • Good for studying metabolism and physiology

    Complex Medium

    • Composed of animal digests or plant products
    • Needed for microbes with unknown growth requirements

    Growth Media

    • Selective media inhibits the growth of certain organisms while allowing others to grow
    • Differential media provides different visual appearances of colonies

    Liquid Medium

    • Provides consistent conditions for microbes

    Solid Medium

    • Used for isolating individual colonies

    Bacterial Cell Division

    • Binary fission is the division of a cell

    Binary Fission

    • Occurs in three steps: DNA replication and segregation, cytokinesis, synthesis of a new cell wall

    Measuring Population Growth

    • Direct Count is done using a Petroff-Hausser counting chamber to count cells rapidly
    • Viable Count determines living cells by counting colonies after serially diluting a sample of cells

    Growth Phases in Batch Culture

    • Lag Phase: The bacteria adapt to new conditions
    • Logarithmic (Log) Phase: Rapid growth and nutrient use
    • Stationary Phase: Growth slows down due to limited nutrients
    • Death Phase: Cells die due to lack of energy for maintenance

    Growth in a Continuous Culture

    • Continuous cultures are used to grow microbes for an extended period of time
    • It is important to maintain adequate nutrient levels and control the growth rate

    Factors Affecting Microbial Growth

    • Temperature
    • pH
    • Osmotic strength
    • Oxygen levels

    Factors Affecting Microbial Growth: Temperature

    • Psychrophile: Growth in cold temperatures
    • Mesophile: Growth in moderate temperatures
    • Thermophile: Growth in hot temperatures
    • Hyperthermophile: Growth in very hot temperatures

    Factors Affecting Microbial Growth: pH

    • Acidophile: Growth in acidic environments
    • Neutrophile: Growth in neutral pH environments
    • Alkalophile: Growth in alkaline environments

    Factors Affecting Microbial Growth: Osmotic Strength

    • Nonhalophile: Cannot tolerate high salt concentrations
    • Halotolerant: Tolerate some salt concentrations
    • Halophile: Requires high salt concentrations
    • Extreme Halophile: Requires very high salt concentrations

    Factors Affecting Microbial Growth: Oxygen Levels

    • Obligate Aerobe: Requires oxygen for growth
    • Facultative Anaerobe: Can grow with or without oxygen
    • Aerotolerant Anaerobe: Can tolerate oxygen but does not use it for growth
    • Obligate Anaerobe: Cannot tolerate oxygen
    • Microaerophile: Requires low oxygen levels

    Cell Structure and Function Part 2

    • Transglycosylase: Forms glycan chains
    • Transpeptidase: Cross-links peptide side chains
    • Autolysins: Cut glycan chains for cell wall expansion
    • Bactoprenol: Lipid carrier for cell wall precursors
    • PBPs: Penicillin Binding Proteins catalyze the glycosyl transferase and transpeptidase activities

    Bacterial Cell Wall Structures

    • Gram-positive bacteria: Have a thick peptidoglycan layer
    • Gram-negative bacteria: Have a thin layer of pepotidoglycan

    Cell Wall Structures: Peptidoglycan

    • The cell wall is made up of interconnected glycan chains
    • The cell wall prevents the cell from lysing.
    • The cell wall provides the cell with a shape.
    • The cell wall is also called murein.

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    Description

    This quiz covers key concepts related to glycolysis, fermentation, respiration, the electron transport chain, and ATP synthesis. You will be tested on your understanding of these metabolic processes and their roles in energy production. Perfect for students studying biochemistry or cellular biology.

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