Microbial Metabolism and ATP Production
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Questions and Answers

What function do the spikes on viruses serve?

  • They protect the virus from heat.
  • They are used to reproduce the virus.
  • They help the virus attach to and enter a host cell. (correct)
  • They assist in the virus' replication within the host.

    • What is meant by the term 'tropism' in the context of viruses?

  • The specific host and tissue types a virus can infect. (correct)
  • The speed at which a virus can spread.
  • The structural characteristics of a virus.
  • The ability of the virus to mutate rapidly.

    • Which of the following viruses exhibits tropism for the respiratory tract?

  • Influenza virus (correct)
  • Poliovirus
  • HIV virus
  • Ebola virus

    • Who is credited as the original discoverer of viruses?

    <p>Dimitri Ivanovski</p> Signup and view all the answers

    How are viruses classified based on their shape?

    <p>Helical and polyhedral</p> Signup and view all the answers

    What is the overall net gain from the breakdown of a single glucose molecule during glycolysis?

    <p>Two ATP, two NADH, and two pyruvate</p> Signup and view all the answers

    What process generates ATP using light energy absorbed by chlorophyll molecules?

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

    Which method is the primary way for generating ATP in most cells?

    <p>Oxidative phosphorylation</p> Signup and view all the answers

    In oxidative phosphorylation, what is the ultimate electron acceptor?

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

    What drives ATP synthesis in photophosphorylation?

    <p>Proton gradient across a membrane</p> Signup and view all the answers

    What mechanism directly transfers a phosphate group to ADP, producing ATP?

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

    Which of the following is not a product of glycolysis?

    <p>FADH2</p> Signup and view all the answers

    How do protons contribute to ATP production during oxidative phosphorylation?

    <p>They create a chemical gradient</p> Signup and view all the answers

    What characterizes the protein PrPsc in relation to PrPc?

    <p>PrPsc can infect and misfold normal proteins like PrPc.</p> Signup and view all the answers

    What is the primary cause of brain damage in Transmissible Spongiform Encephalopathy (TSE)?

    <p>Accumulation of rogue proteins forming plaques.</p> Signup and view all the answers

    Which of the following is NOT a type of TSE found in humans?

    <p>Mad Cow Disease</p> Signup and view all the answers

    Why are prions considered extremely resilient pathogens?

    <p>They can survive standard sterilization procedures.</p> Signup and view all the answers

    What are the potential consequences of TSE on affected individuals?

    <p>They may suffer from loss of motor coordination and dementia.</p> Signup and view all the answers

    What do plaques in a bacterial lawn correspond to?

    <p>Plaque-forming units (PFU)</p> Signup and view all the answers

    Which method is used to detect the presence of RNA viruses?

    <p>RT-PCR</p> Signup and view all the answers

    What are cytopathic effects (CPEs)?

    <p>Observable cell abnormalities due to viral infections</p> Signup and view all the answers

    In which environment do animal viruses require for replication?

    <p>In vivo or in vitro conditions</p> Signup and view all the answers

    What is a key characteristic of viroids?

    <p>They consist only of a short strand of circular RNA.</p> Signup and view all the answers

    What could be a possible outcome of viral infection in a developing embryo?

    <p>Disruption of embryonic development</p> Signup and view all the answers

    Which of the following describes the use of serological tests?

    <p>To detect specific viruses in patient serum</p> Signup and view all the answers

    What type of cells are typically associated with carcinomas and sarcomas due to viral transformation?

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

    What is the function of the reaction center in the photosystem?

    <p>To undergo oxidation upon excitation and give up an electron</p> Signup and view all the answers

    What is produced as a byproduct of oxygenic photosynthesis?

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

    What are thylakoids in prokaryotes?

    <p>Infolded regions of the plasma membrane</p> Signup and view all the answers

    Which of the following is NOT a component of a photosystem?

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

    In oxygenic photosynthesis, what is the primary electron source?

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

    Which type of photosynthesis does cyanobacteria perform?

    <p>Only oxygenic photosynthesis</p> Signup and view all the answers

    What is the main role of the light-harvesting complex within a photosystem?

    <p>To absorb and transfer light energy to the reaction center</p> Signup and view all the answers

    What is generated as a result of anoxygenic photosynthesis?

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

    What is a cytokine storm most likely to cause?

    <p>Life-threatening multi-organ failure</p> Signup and view all the answers

    What is the main function of superantigens?

    <p>To promote nonspecific stimulation of immune cells</p> Signup and view all the answers

    Which of the following organisms is the prototype superantigen associated with toxic shock syndrome?

    <p>Staphylococcus aureus</p> Signup and view all the answers

    Which component is identified as an endotoxin?

    <p>Lipopolysaccharides from gram-negative bacteria</p> Signup and view all the answers

    Why do superantigens stimulate a larger proportion of T cells compared to normal antigens?

    <p>Superantigens cause a direct crosslinking of T cell receptors and MHC II.</p> Signup and view all the answers

    Study Notes

    Microbial Metabolism

    • Substrate Level Phosphorylation is one of two mechanisms for producing ATP.
    • In substrate-level phosphorylation, a phosphate group is removed from an organic molecule and directly transferred to ADP, producing ATP.
    • During glycolysis, high-energy phosphate groups from intermediate molecules are added to ADP to produce ATP.
    • Overall, during glycolysis, the net gain from the breakdown of a single glucose molecule is two ATP molecules, two NADH molecules, and two pyruvate molecules.

    Photophosphorylation

    • Photophosphorylation is the process plants use to convert ADP into ATP during photosynthesis.
    • It involves the movement of electrons through an electron transport chain.
    • This generates a proton gradient.
    • The energy is absorbed by chlorophyll molecules.

    Oxidative Phosphorylation

    • Oxidative Phosphorylation is a cellular process that generates ATP.
    • It uses an electron transport chain to transfer electrons from NADH and FADH2 to oxygen.
    • The energy released is used to pump protons across a membrane.
    • This creates a gradient, driving ATP synthesis through ATP synthase.
    • Ion pumps are used to pump H+ out of the bacterial cytoplasm into the extracellular space.
    • H+ flow back through ATP synthase, providing the energy for ATP production.

    Respiration vs. Fermentation

    • Cellular respiration is the breakdown of molecules in the presence of oxygen.
    • Fermentation is the breakdown of molecules in the absence of oxygen.

    Glycolysis Pathways

    • The Embden-Meyerhof-Parnas (EMP) pathway is a type of glycolysis found in animals and is the most common in microbes.
    • Glycolysis in EMP pathway consists of two distinct phases: energy investment and energy payoff—using 2 ATP and producing 4 ATP—resulting in a net gain of 2 ATP with 2 NADH from one glucose molecule.
    • The Entner-Doudoroff (ED) pathway is another pathway.
    • The pentose phosphate pathway (PPP) pathway is also called phosphogluconate pathway or the hexose monophosphate shunt.

    Pentose Phosphate Pathway (PPP)

    • PPP yields NADPH and five-carbon sugars as well as ribose 5-phosphate.
    • One glucose produces two molecules of pyruvate.
    • Glycolysis, Breakdown of pyruvate, Citric acid cycle, and Oxidative phosphorylation occur in bacteria and eukaryotic cells in different locations.

    Transition Reaction, Coenzyme A, and the Krebs Cycle

    • Pyruvate first needs to be decarboxylated.
    • A two-carbon acetyl group is attached to coenzyme A.
    • The two-carbon acetyl group is attached to coenzyme A (CoA).
    • Electrons are transferred to NAD+ to form NADH.
    • Occurs in the mitochondrial matrix of eukaryotes and in the cytoplasm of prokaryotes.
    • Also called the citric acid cycle, or the tricarboxylic acid cycle (TCA).

    Transition Reaction, Coenzyme A, and the Krebs Cycle (continued)

    • Electrons are transferred during oxidation.
    • Acetyl CoA enters the TCA cycle.

    Comparison of Respiration vs. Fermentation

    • Summarized data concerning respiration versus fermentation are provided.

    Photosynthesis (General)

    • Photosynthesis is when phototrophic organisms convert solar energy to chemical energy.
    • Two sequential stages: light-dependent and light-independent.

    Light-Dependent Reactions

    • Energy from sunlight is converted into stored chemical energy.
    • Produces ATP, O2, and either NADPH or NADH to store energy temporarily.

    Light-Independent Reactions (Calvin Cycle)

    • Chemical energy from light-dependent is used to build sugar energy molecules.

    Photosynthetic Structures (Prokaryotes and Eukaryotes)

    • In prokaryotes: Photosynthetic membranes aren't organized into distinct, membrane-enclosed organelles, but are infolded regions of the plasma membrane.
    • In eukaryotes: Photosynthesis occurs within chloroplasts, which have three membranes (inner, outer, thylakoids).
    • Thylakoids are disc-shaped photosynthetic structures arranged in stacks called granum.

    Oxygenic Photosynthesis

    • In oxygenic photosynthesis, water is split and provides the electron needed in the reaction center.
    • Oxygen is a byproduct.
    • The process occurs in eukaryotes and cyanobacteria.

    Anoxygenic Photosynthesis

    • Uses a different electron donor instead of water.
    • Does not produce oxygen.

    Acellular Pathogens (Viruses)

    • Viruses are infectious, acellular pathogens.
    • They need a host cell to reproduce
    • They have a protein capsid surrounding their nucleic acid (DNA or RNA).
    • Virion is the complete, infective form of a virus outside the host cell.
    • Viral structures include: capsid, viral genome, sheath, and tail fibers.
    • Viruses can be helical, polyhedral or complex in shape.
    • Viruses can be enveloped or naked.
    • Viral replication cycles vary.
    • Some viruses replicate in the cytoplasm, whereas others replicate in the nucleus.
    • Enzymes such as reverse transcriptase are used at different stages of the replication cycles.
    • Viruses use different methods (e.g., attachment, penetration, uncoating, replication, assembly, and release) of replication cycles.
    • Know basic viral diseases.
    • The process of horizontal gene transfer where DNA or RNA is moved to a different cell (transduction, transformation, and conjugation)

    Cytopathic Effects (CPEs)

    • Observable cell abnormalities; distinct changes in shape, or shrinkage of nucleus or cytoplasm.
    • Normal cells are transformed, and inclusion bodies might be observed.

    Characteristics of Viruses

    • Infectious, acellular pathogens.
    • Have a unique genome made up of DNA or RNA.
    • Intracellular obligate parasites.
    • Host/cell type specificity may vary.

    Viroids

    • Consist of a short strand of circular RNA.
    • They don't have a protein coat.
    • They can self-replicate.
    • They can cause diseases in plants.

    Prions

    • Misfolded rogue proteins.
    • Can be infectious.
    • Stimulate other proteins to misfold, forming plaques.
    • Cause Transmissible spongiform encephalopathy (TSE).

    Bacterial Pathogenic Mechanisms

    • Acute: hours, days, or weeks
    • Chronic: month, years or lifetime
    • Latent: dormant for extended periods with no active replication.
    • Asymptomatic: no noticeable signs.

    Endotoxins vs Exotoxins

    • Endotoxins are part of the gram negative outer membrane, liberated when the bacteria die.
    • Exotoxins are protein produced inside pathogenic bacteria. Most commonly gram-positive, secreted or released during lysis.
    • The roles of exotoxin are: intracellular targeting, membrane disruption, or superantigens.
    • Heat stability and LD50 (median lethal dose) characteristics of exotoxins and endotoxins provided.

    Viral Growth Curve

    • In a one-step multiplication curve, host cells lyse, releasing a large number of viral particles.
    • During eclipse, the viral particles penetrate and fuse with the host cells.

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    Midterm Exam 3 FA24 Study Guide PDF

    Description

    Explore the concepts of microbial metabolism, focusing on the processes of substrate-level phosphorylation, photophosphorylation, and oxidative phosphorylation. This quiz will test your understanding of how ATP is produced through different biochemical pathways in living organisms.

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