Cellular Respiration and Fermentation Quiz
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Questions and Answers

What happens to the electron transport chain (ETC) in the absence of O2?

  • ETC generates more ATP.
  • ETC becomes more efficient.
  • ETC cannot operate. (correct)
  • ETC continues to operate normally.

    • Which process couples with glycolysis to produce ATP in anaerobic conditions?

  • Substrate-level phosphorylation
  • Fermentation (correct)
  • Protein synthesis
  • Oxidative phosphorylation

    • What is a primary function of fermentation in cells?

  • To produce oxygen.
  • To enhance aerobic respiration.
  • To regenerate NAD+ for glycolysis. (correct)
  • To completely oxidize glucose.

    • What type of phosphorylation is utilized during fermentation to generate ATP?

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

    Which types of fermentation are mentioned in the content?

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

    What is the primary molecule that is formed from ADP and Pi by the catalytic sites in the catalytic knob during oxidative phosphorylation?

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

    What is the approximate percentage of energy from glucose that is converted into ATP during cellular respiration?

    <p>34%</p> Signup and view all the answers

    In anaerobic respiration, what type of final electron acceptors are used by some prokaryotic organisms?

    <p>Less electronegative molecules like SO4^2- or NO3^-</p> Signup and view all the answers

    Which step in cellular respiration involves the electron transport chain (ETC)?

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

    What happens to the energy that is not converted into ATP during cellular respiration?

    <p>It is lost as heat.</p> Signup and view all the answers

    What is the main difference between aerobic and anaerobic respiration?

    <p>Aerobic respiration requires oxygen while anaerobic respiration does not.</p> Signup and view all the answers

    Which compounds can serve as fuel in cellular respiration?

    <p>Carbohydrates, fats, and proteins</p> Signup and view all the answers

    What role does the reducing agent play in a redox reaction?

    <p>It donates electrons to another reactant.</p> Signup and view all the answers

    Which of the following is a product of aerobic respiration?

    <p>Carbon dioxide</p> Signup and view all the answers

    What is the first stage of cellular respiration?

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

    How do redox reactions relate to energy release during cellular respiration?

    <p>They transfer electrons, releasing energy stored in organic molecules.</p> Signup and view all the answers

    What characterizes cellular respiration?

    <p>It includes both aerobic and anaerobic respiration.</p> Signup and view all the answers

    What is the end product of glycolysis?

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

    What is the primary function of the energy released as electrons are passed down the electron transport chain (ETC)?

    <p>To pump H+ ions from the mitochondrial matrix to the intermembrane space</p> Signup and view all the answers

    In what manner do H+ ions contribute to the production of ATP in the process of chemiosmosis?

    <p>They generate a mechanical rotation in ATP synthase which phosphorylates ADP</p> Signup and view all the answers

    What happens to H+ ions after they pass through the ATP synthase complex?

    <p>They exit into the mitochondrial matrix</p> Signup and view all the answers

    Which of the following best describes the process of chemiosmosis?

    <p>The coupling of energy from a proton gradient to drive the synthesis of ATP</p> Signup and view all the answers

    What is the result of H+ ions binding to the rotor of ATP synthase?

    <p>It causes changes in the rotor's shape, leading to mechanical movement</p> Signup and view all the answers

    What percentage of ATP production is accounted for by oxidative phosphorylation?

    <p>90%</p> Signup and view all the answers

    Which process involves the transfer of a phosphate group from a substrate to ADP?

    <p>Substrate-Level Phosphorylation</p> Signup and view all the answers

    Where does glycolysis take place within the cell?

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

    What is the net production of ATP from one glucose molecule during glycolysis?

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

    Which component of cellular respiration is responsible for generating no ATP directly?

    <p>Electron Transport Chain</p> Signup and view all the answers

    What is the terminal electron acceptor in the electron transport chain?

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

    What is the maximum number of ATP molecules produced per glucose during cellular respiration?

    <p>32</p> Signup and view all the answers

    How do electrons behave as they move through the electron transport chain?

    <p>They lose free energy</p> Signup and view all the answers

    Which phase of glycolysis involves the expenditure of energy?

    <p>Energy investment phase</p> Signup and view all the answers

    Which of the following best describes the main function of the electron transport chain?

    <p>To transfer electrons in a series of reactions</p> Signup and view all the answers

    What is produced as a result of pyruvate conversion in alcohol fermentation?

    <p>Ethanol and NAD+</p> Signup and view all the answers

    Which process is characterized by the reduction of pyruvate using NADH?

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

    What is the net ATP yield from fermentation per glucose molecule?

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

    During strenuous exercise, human muscle cells switch from aerobic respiration to which of the following?

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

    What role does NAD+ play during glycolysis?

    <p>It acts as the oxidizing agent.</p> Signup and view all the answers

    What distinguishes fermentation from cellular respiration?

    <p>Fermentation functions without the electron transport chain.</p> Signup and view all the answers

    Which of the following is NOT a product of lactic acid fermentation?

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

    Which of the following sources can be metabolized for energy in cellular respiration?

    <p>Proteins and fats</p> Signup and view all the answers

    What is the primary location of glycolysis in the cell?

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

    What distinguishes fermentation's final electron acceptors from those in cellular respiration?

    <p>Fermentation uses organic molecules, while cellular respiration transfers electrons to the electron transport chain.</p> Signup and view all the answers

    Study Notes

    Learning Objectives

    • Cellular Respiration and Fermentation, Chapter 9, details energy release from food and redox reaction processes in cellular metabolism.
    • It covers the major steps in cellular respiration (glycolysis, etc.) and the importance of NAD+/NADH.
    • Electron transport down the ETC is coupled with ATP production via chemiosmosis.
    • Students will compare fermentation types to cellular respiration (aerobic and anaerobic).

    Obtaining Cellular Energy

    • Cells require energy from external sources to perform work, including mechanical, chemical, and transport functions.
    • Organisms obtain energy by ingesting other animals or performing photosynthesis.

    Energy Flows and Chemicals Cycle

    • Energy enters ecosystems as light and leaves as heat.
    • Chemical elements are recycled in ecosystems, such as carbon and nitrogen cycles.

    Energy Flows and Chemicals Cycle (continued)

    • Photosynthesis converts light energy into organic molecules and oxygen, which, in turn, feeds cellular respiration.
    • Cells use the stored chemical energy in organic molecules to produce ATP, which is critical for cellular work.

    Catabolic Pathways

    • Catabolic pathways release stored energy by breaking down complex molecules (fuel).
    • Breaking down complex molecules releases electrons and these are central to respiration processes.
    • Glucose is a common molecule broken down in respiration. Its chemical equation is: C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy (ATP + heat).

    Different Catabolic Pathways to Produce ATP

    • The breakdown of organic molecules is an exergonic process.
    • These molecules are often called fuels.
    • Fermentation is a partial sugar breakdown without oxygen. This is a pathway often used to produce wine, cheese, beer and bread, and extracts energy simply from glycolysis..

    Different Catabolic Pathways to Produce ATP (continued)

    • Aerobic respiration is a chemical process that uses organic molecules and oxygen to produce ATP.
    • It is a common process in most eukaryotic cells and many prokaryotic cells.

    Different Catabolic Pathways to Produce ATP (continued)

    • Anaerobic respiration is similar to aerobic respiration, but uses compounds other than oxygen (e.g., NO3- or SO42-).
    • Cellular respiration is a broad term and often refers only to aerobic respiration since it is most common in cells.

    In Cellular Respiration, Electrons are Transferred

    • Electrons are transferred during chemical reactions in organic molecules.
    • This releases energy, used to synthesize ATP.
    • Chemical reactions moving electrons are called oxidation-reduction (redox) reactions.

    Redox Reactions

    • The electron donor is the reducing agent.
    • The electron receptor is the oxidizing agent.
    • Some redox reactions don't transfer electrons, but change electron sharing in covalent bonds instead.

    The Steps of Cellular Respiration

    • Glycolysis breaks down glucose to pyruvate.
    • The citric acid cycle completes the breakdown of glucose.
    • Oxidative phosphorylation accounts for most ATP synthesis (~90%).

    Overview of Cellular Respiration

    • Glycolysis occurs in the cytosol, breaking glucose into pyruvate and producing electrons via NADH.
    • Pyruvate oxidation moves into the mitochondria, producing Acetyl CoA which enters the citric acid cycle, creating further electrons via NADH and FADH2.
    • Oxidative phosphorylation uses electron transport to create a proton gradient, providing energy to produce ATP by ATP synthase.

    ATP Production via Phosphorylation

    • Oxidative phosphorylation is primarily powered by redox reactions of the electron transport chain.
    • It is responsible for ~90% of ATP production.
    • Substrate-level phosphorylation occurs from enzyme transfer of phosphate to ADP, but produces a much smaller yield of ATP than oxidative phosphorylation.

    Glycolysis:

    • Glycolysis breaks down glucose into two pyruvate molecules.
    • This occurs in the cytosol and does not need oxygen.
    • The glycolysis process is in two phases, which involves both the breaking down and subsequent reorganisation of the original molecule.

    2 Major Phases of Glycolysis:

    • Energy investment phase: cells use 2 ATP to start the process
    • Energy payoff phase: cell produces 4 ATP and 2 NADH + 2H+

    Electron Transport Chain (ETC)

    • The ETC is located in the inner membrane (cristae) of mitochondria.
    • Most of the components are multi-protein complexes.
    • The ETC moves electrons from NADH & FADH2 to O2 forming H2O.

    Electron Transport Chain (ETC) - continued

    • Electrons lose energy as they move along the ETC and this energy is used to pump protons (H+) into the intermembrane compartment.
    • This builds a proton concentration gradient.

    Electron Transport Chain and Chemiosmosis

    • The proton gradient produced by the ETC is used to power ATP synthase, which is also located in the inner membrane.
    • H+ move from high to low concentrations across the membrane
    • ATP is generated.

    Chemiosmosis

    • Chemiosmosis is the use of a proton (H+) gradient to drive cellular work.
    • H+ ions move into binding sites on the rotor of ATP synthase.
    • This spins and helps catalyze phosphorylation of ADP to ATP
    • This helps produce ATP.

    Oxidative Phosphorylation

    • Oxidative phosphorylation is a process that produces ATP using the electron transport chain.

    An Audit of ATP Production

    • During cellular respiration, most energy flows from glucose to NADH/FADH2 to the ETC, then to proton-motive force and finally ATP.
    • Typically about 30-32 ATP per glucose molecule and the remaining energy is lost as heat.

    An Audit of ATP Production (continued)

    • ATP production depends on how electrons from cytosolic NADH cross the mitochondrial membrane.

    Anaerobic Respiration

    • Some prokaryotes use electron transport chains, but do not use oxygen as the final acceptor.
    • This process typically produces less energy, and no water.

    Fermentation

    • Fermentation occurs in the absence of oxygen.
    • Fermentation is coupled with glycolysis.
    • It regenerates NAD+ so glycolysis can continue, producing a small amount of ATP.

    Fermentation and Types of Fermentation

    • Fermentation uses substrate-level phosphorylation to generate ATP.
    • It includes reactions after glycolysis that regenerate NADH so glycolysis can continue.
    • Two major types are alcohol and lactic acid fermentation

    Alcohol Fermentation

    • Pyruvate is converted to ethanol.
    • CO2 is released.
    • NAD+ is regenerated.

    Lactic Acid Fermentation

    • Pyruvate is converted to lactate to regenerate NAD+.
    • No CO2 is released.

    Comparing Fermentation with Aerobic and Anaerobic Respiration

    • All of these processes use glycolysis to oxidize glucose and harvest energy (chemical).
    • NAD+ is the oxidizing agent that accepts electrons in glycolysis.
    • Aerobic respiration produces greater ATP than fermentation or anaerobic respiration.

    Glycolysis During Evolution

    • Glycolysis is present in both prokaryotic and eukaryotic cells.
    • It does not require membrane-bound organelles.
    • It likely evolved before oxygen was common in the atmosphere.

    Energy from Multiple Sources

    • Catabolic pathways funnel electrons from various organic molecules (e.g., carbohydrates, proteins, fats) into cellular respiration.

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    Description

    Test your knowledge on cellular respiration, including the electron transport chain, glycolysis, and fermentation processes. This quiz explores aerobic and anaerobic pathways, energy production, and the role of different molecules in ATP generation. Perfect for students studying biology or biochemistry!

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