Cell Respiration and Energy Transformations
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What is the primary structural role of ribose in ATP?

  • It acts as a nitrogenous base for nucleotide pairing.
  • It acts as a catalyst for ATP hydrolysis reaction.
  • It serves as a five-carbon sugar that connects the base and phosphate groups. (correct)
  • It provides a negatively charged component for energy transfer.

    • Which characteristic of ATP makes it specifically suitable as the 'energy currency' of the cell?

  • Its ability to release a small, manageable amount of energy during hydrolysis. (correct)
  • Its high stability, making it resistant to unwanted side reactions.
  • Its complex ring structure, allowing it to store large quantities of energy.
  • Its high molecular weight allows for efficient transfer and storage of energy.

    • During which of the following macromolecule synthesis processes is ATP NOT directly utilized?

  • Protein translation
  • Lipid synthesis (correct)
  • DNA replication
  • RNA transcription

    • What role does ATP play in active transport across cell membranes?

    <p>It provides the energy for the change from the stable to less stable pump protein conformation.</p> Signup and view all the answers

    How do muscle cells utilize ATP to facilitate movement?

    <p>ATP powers the interaction of actin and myosin filaments to slide across each other with force.</p> Signup and view all the answers

    What is the major energy transformation that occurs when ATP is hydrolyzed?

    <p>Chemical potential energy is converted to a low, readily available form of energy.</p> Signup and view all the answers

    Comparing ATP and ADP, which molecule contains more chemical potential energy?

    <p>ATP contains more chemical potential energy.</p> Signup and view all the answers

    What happens to the released energy during ATP hydrolysis, if it was to large quantity or was released to rapidly?

    <p>The excess energy would be converted into heat and wasted.</p> Signup and view all the answers

    How many ATP molecules are produced directly from each bisphosphoglycerate molecule during glycolysis?

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

    What is the net yield of ATP molecules from glycolysis per glucose molecule?

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

    What is the primary role of NAD in respiration?

    <p>To function as an electron carrier.</p> Signup and view all the answers

    What is the primary function of converting pyruvate to lactate during anaerobic respiration?

    <p>To regenerate NAD</p> Signup and view all the answers

    How many electrons are accepted by NAD+ during its reduction?

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

    In the Krebs cycle, what is the primary role of NAD and FAD?

    <p>To carry electrons and protons.</p> Signup and view all the answers

    What is produced by the oxidation stage of glycolysis?

    <p>Reduced NAD and organic acid</p> Signup and view all the answers

    Which molecule acts as the final electron acceptor during the conversion of pyruvate to lactate?

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

    What is the immediate result of FAD or NAD accepting a pair of electrons?

    <p>They become reduced.</p> Signup and view all the answers

    What is the initial step in glycolysis that makes the glucose molecule more reactive?

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

    What is the end product of ethanol fermentation in yeast?

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

    Where do reduced NAD and reduced FAD transfer the electrons they are holding?

    <p>To the electron transport chain.</p> Signup and view all the answers

    In glycolysis, which molecule is split into two triose phosphate molecules?

    <p>Fructose bisphosphate</p> Signup and view all the answers

    During one turn of the Krebs cycle, how many molecules of carbon dioxide are released?

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

    Why is yeast described as a facultative anaerobe?

    <p>It can respire both aerobically and anaerobically</p> Signup and view all the answers

    What is the function of the electron transport chain in the inner mitochondrial membrane?

    <p>To pass electrons and pump protons.</p> Signup and view all the answers

    How is ATP produced during the final stage of glycolysis?

    <p>By transfer of phosphate groups to ADP.</p> Signup and view all the answers

    In baking, what is the purpose of the carbon dioxide produced by yeast?

    <p>To provide air pockets making the bread light</p> Signup and view all the answers

    Where do the two hydrogen atoms used to reduce pyruvate to lactate come from?

    <p>Reduced NAD</p> Signup and view all the answers

    What happens to the hydrogen atoms removed during oxidation in glycolysis?

    <p>They are accepted by NAD.</p> Signup and view all the answers

    How does the electron transport chain contribute to the generation of a proton gradient?

    <p>By pumping protons across the inner mitochondrial membrane.</p> Signup and view all the answers

    Where does glycolysis take place within a cell?

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

    How many protons are pumped by the third main electron carrier for each pair of electrons?

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

    What is the role of ATP synthase in chemiosmosis?

    <p>To utilize the proton gradient to produce ATP.</p> Signup and view all the answers

    What directly causes P680 to become oxidized in photosystem II?

    <p>Absorption of light photons.</p> Signup and view all the answers

    The oxygen evolving complex (OEC) of photosystem II is responsible for which of the following?

    <p>Splitting water molecules to restore electrons to the reaction center.</p> Signup and view all the answers

    What is the immediate destination of the electrons released by P680 in photosystem II?

    <p>An electron transport chain.</p> Signup and view all the answers

    Why does the splitting of water in photosystem II happen only in the light?

    <p>P680 only becomes oxidized when it absorbs light.</p> Signup and view all the answers

    How do the protons released from photolysis contribute to ATP production?

    <p>By increasing the proton concentration in the thylakoid space.</p> Signup and view all the answers

    What is the direct role of plastoquinone in the electron transport chain?

    <p>To accept electrons from photosystem II and pump protons into the thylakoid space.</p> Signup and view all the answers

    Compared to electrons released by photosystem II, how do the electrons entering photosystem I differ?

    <p>They have less potential energy.</p> Signup and view all the answers

    What is the primary source of energy used to generate the proton gradient across the thylakoid membrane?

    <p>Energy released from electrons as they move through the electron transport chain and photolysis of water.</p> Signup and view all the answers

    What is the initial carbon source utilized by photosynthetic organisms?

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

    What is the immediate product formed after carbon dioxide is fixed by Rubisco?

    <p>Glycerate-3-phosphate</p> Signup and view all the answers

    Which compound reacts directly with carbon dioxide during the carbon fixation process?

    <p>Ribulose bisphosphate</p> Signup and view all the answers

    What molecules supply the energy and electrons required to convert glycerate-3-phosphate (GP) into triose phosphate (TP)?

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

    What is the primary result of adding hydrogen to glycerate-3-phosphate?

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

    In the Calvin cycle, where does the conversion of glycerate-3-phosphate to triose phosphate take place?

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

    What is the first carbohydrate product of the light-independent reactions of photosynthesis?

    <p>Triose phosphate</p> Signup and view all the answers

    Why is the regeneration of RuBP crucial for the Calvin cycle?

    <p>To ensure continuous carbon fixation</p> Signup and view all the answers

    Study Notes

    Cell Respiration

    • ATP is a nucleotide consisting of adenine, ribose, and three phosphate groups. Its negative charges make it suitable for energy transfer.
    • ATP hydrolysis releases small amounts of energy, sufficient for cellular processes, but not wasted as heat.
    • ATP is used for synthesizing macromolecules like DNA, RNA, and proteins. This involves linking monomers.
    • ATP powers active transport against concentration gradients, changing protein pump conformations.
    • Muscle contraction relies on actin and myosin sliding, fueled by ATP to exert force.

    Energy Transformations

    • ATP stores more chemical energy than ADP; hydrolysis releases energy for cellular processes.
    • The phosphate group's detachment from a molecule (e.g., protein pump, substrate) releases energy, driving changes (conformational or chemical).
    • ATP synthesis can use glucose, fats, or protein oxidation; or light energy (photosynthesis); or inorganic substance oxidation (chemosynthesis) to replenish itself.

    Cell Respiration vs. Gas exchange

    • Cellular respiration is producing ATP through the breakdown of organic molecules.
    • Gas exchange involves oxygen intake and carbon dioxide release, which both rely on concentration differences.
    • Gas exchange supports cell respiration by providing oxygen and removing carbon dioxide.
    • Respiration produces carbon dioxide, therefore gas exchange must occur to remove it from cells.

    Anaerobic & Aerobic Respiration

    • Aerobic respiration requires oxygen; products are carbon dioxide and water. Yields more ATP (30+).
    • Uses glucose, lipids, and amino acids as substrates.
    • Anaerobic respiration does not require oxygen; products depend on the type (e.g., lactate or ethanol). Yields less ATP (2).
    • Uses only glucose as a substrate

    Pyruvate to Acetyl CoA

    • The link reaction converts pyruvate to acetyl CoA, releasing carbon dioxide and transferring electrons.
    • The resulting acetyl CoA enters the Krebs cycle.
    • This reaction is crucial for transferring energy for aerobic respiration.

    Krebs Cycle

    • Acetyl CoA enters the Krebs cycle, oxidizing carbon compounds to produce carbon dioxide, reducing NAD and FAD (electron carriers) and forming ATP through substrate-level phosphorylation.
    • It breaks down carbon atoms from substrates like glucose, fat, and protein in the cycle.
    • Oxidation and decarboxylation reactions are crucial steps releasing energy.

    Electron Transport Chain

    • Electrons from NADH and FADH2 travel down the electron transport chain (ETC).
    • Electrons are transferred, releasing energy that creates a proton gradient across the inner mitochondrial membrane.
    • ATP is created from ADP through chemiosmosis as protons flow through ATP synthase.
    • Oxygen is the final electron acceptor, forming water in the process.

    Photosynthesis

    • Light energy absorbed by pigments (like chlorophyll) in thylakoid membranes converts light energy to chemical energy.
    • Photosystems capture and transfer light energy to create ATP and NADPH.
    • The Calvin cycle uses ATP, NADPH, and atmospheric CO2 to synthesize glucose.
    • Oxygen is released as a byproduct of photosynthesis.

    Photosystem Components

    • Photosystems are pigment-protein complexes containing chlorophyll.
    • Light energy excites electrons in chlorophyll, initiating electron transport.
    • Water is split (photolysis) to replace lost electrons.
    • Electrons pass through an electron transport chain, generating a proton gradient.

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    Description

    This quiz covers essential concepts of cell respiration, focusing on ATP structure and its role in energy transfer and cellular processes. It also discusses the mechanisms of energy transformations in cells, including ATP synthesis from various sources. Test your understanding of how ATP powers biological functions and muscle contractions.

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