Energy and Metabolism Overview
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Questions and Answers

What is the difference between catabolism and anabolism?

  • Catabolism breaks molecules down to produce energy, while anabolism builds up body tissues. (correct)
  • Catabolism and anabolism are the same processes with different names.
  • Catabolism stores energy, while anabolism releases it.
  • Catabolism builds molecules, while anabolism breaks them down.

    • Which type of work involves moving molecules across membranes?

  • Transport Work (correct)
  • Chemical Work
  • Thermal Work
  • Mechanical Work

    • What happens to the oxidation state of a molecule during oxidation?

  • It remains unchanged.
  • It increases as the molecule loses electrons. (correct)
  • It decreases as the molecule gains electrons.
  • It fluctuates depending on the medium.

    • What role do activated carrier molecules play in cellular energy transformations?

    <p>They store and transfer energy captured from metabolic processes.</p> Signup and view all the answers

    How does lowering activation energy affect reaction rates?

    <p>It generally increases the reaction rates.</p> Signup and view all the answers

    What is the transition state in enzyme-catalyzed reactions?

    <p>The high-energy state between reactants and products.</p> Signup and view all the answers

    What defines the active site of an enzyme?

    <p>The region where the substrate binds and the reaction occurs.</p> Signup and view all the answers

    What effect do enzymes have on the activation energy of a reaction?

    <p>They stabilize the transition state, effectively lowering the activation energy.</p> Signup and view all the answers

    What does Vmax represent in enzyme kinetics?

    <p>The maximum rate of reaction when the enzyme is fully saturated with substrate</p> Signup and view all the answers

    Which statement best describes Km?

    <p>It is the substrate concentration at which the reaction rate is half of Vmax</p> Signup and view all the answers

    What distinguishes competitive inhibition from non-competitive inhibition?

    <p>Competitive inhibitors resemble the substrate and block the active site</p> Signup and view all the answers

    What is a key characteristic of irreversible enzyme inhibition?

    <p>The inhibitor binds covalently and permanently inactivates the enzyme</p> Signup and view all the answers

    How do cofactors differ from coenzymes?

    <p>Coenzymes are organic molecules that transfer chemical groups</p> Signup and view all the answers

    Which effect does increasing temperature have on enzyme activity within a certain limit?

    <p>It speeds up enzymatic reactions until denaturation occurs</p> Signup and view all the answers

    What happens when enzymes are exposed to extreme pH levels?

    <p>Enzymes may change shape, reducing their activity</p> Signup and view all the answers

    What is the primary result of the digestion stage in cellular metabolism?

    <p>Nutrients are broken down into their simplest forms for absorption</p> Signup and view all the answers

    What role do second messengers play in signal transduction?

    <p>They carry signals inside the cell.</p> Signup and view all the answers

    Which type of signaling involves a cell sending signals through the bloodstream to distant cells?

    <p>Endocrine signaling</p> Signup and view all the answers

    Which component acts as the 'worker' in the signal transduction process?

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

    What is the primary function of G-Protein Coupled Receptors (GPCRs) in signal transduction?

    <p>To initiate a cascade of reactions using G proteins.</p> Signup and view all the answers

    Which of the following best describes autocrine signaling?

    <p>Cells signal themselves.</p> Signup and view all the answers

    What distinguishes receptor tyrosine kinases (RTKs) from other receptor types?

    <p>They add phosphate groups to proteins.</p> Signup and view all the answers

    During the adrenaline signaling process in muscle cells, what is the primary result of the signaling cascade?

    <p>Muscle cells break down glycogen into glucose.</p> Signup and view all the answers

    In which type of receptor do ligands typically enter the cell and affect gene expression directly?

    <p>Nuclear receptors</p> Signup and view all the answers

    What is the first step in the activation of Receptor Tyrosine Kinases (RTKs) during signal transduction?

    <p>A signal binds to the RTK and pairs it with another RTK.</p> Signup and view all the answers

    Which of the following molecules is considered a second messenger in cell signaling?

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

    How do membrane receptor-mediated and nuclear receptor-mediated signal transduction mechanisms primarily differ?

    <p>Membrane receptors relay signals from the surface, while nuclear receptors pass signals through the membrane.</p> Signup and view all the answers

    What role do protons play in chemiosmotic coupling within mitochondria?

    <p>They create a chemical gradient that drives ATP synthesis.</p> Signup and view all the answers

    What is the primary function of the β subunits in the FoF1 ATP synthase complex?

    <p>To bind ADP and synthesize ATP through conformational changes.</p> Signup and view all the answers

    What is the primary purpose of glycolysis from a cellular perspective?

    <p>To produce ATP and NADH for quick cellular energy</p> Signup and view all the answers

    During which stage of glycolysis is glucose converted into two identical 3-carbon molecules?

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

    What are the overall inputs required for glycolysis?

    <p>1 Glucose, 2 NAD+, 2 ADP, and 2 Pi</p> Signup and view all the answers

    Why is it essential for cells to regenerate NAD+ after glycolysis?

    <p>NAD+ acts as an electron carrier necessary for glycolysis to continue.</p> Signup and view all the answers

    How do cells regenerate NAD+ in the absence of oxygen?

    <p>By converting pyruvate into lactic acid or ethanol.</p> Signup and view all the answers

    What is the role of acetyl CoA in cellular metabolism?

    <p>To carry energy-rich molecules into the citric acid cycle.</p> Signup and view all the answers

    What are the main products of the citric acid cycle?

    <p>Energy carriers like NADH and FADH2, and CO2 as waste</p> Signup and view all the answers

    What is the energy transformation that occurs during oxidative phosphorylation?

    <p>Addition of inorganic phosphate to ATP using energy from nutrient oxidation.</p> Signup and view all the answers

    Study Notes

    Energy and Metabolism

    • Metabolism encompasses all chemical and physical activities using or converting energy
    • Catabolism breaks down molecules to produce energy
    • Anabolism builds up body tissues and energy stores

    Energy and Cell Work

    • Energy is the capacity to do work
    • Chemical work: molecule synthesis
    • Mechanical work: movement
    • Transport work: molecule movement across membranes

    Oxidation and Reduction

    • Oxidation: molecule loses electrons (or gains oxygen), increasing its oxidation state
    • Reduction: molecule gains electrons (or loses oxygen), decreasing its oxidation state

    Activated Carrier Molecules

    • Store and transfer energy in cells
    • Capture energy from processes like food breakdown, powering activities like muscle contraction and molecule synthesis

    Enzymes and Activation Energy

    • Enzymes lower activation energy, speeding up chemical reactions
    • Activation energy: minimum energy needed to start a reaction
    • Lowering activation energy accelerates reactions

    Enzyme Activity and Substrate Specificity

    • Active site: enzyme region where substrate binds, reacting
    • Substrate: specific molecule upon which an enzyme acts
    • Enzyme's active site shape and properties are specific, like a “lock and key,” ensuring only corresponding substrates bind

    Enzyme Inhibition

    • Competitive inhibition: inhibitor resembles substrate, binding to the active site, blocking substrate binding. It can be overcome by increasing substrate concentration.
    • Non-competitive inhibition: inhibitor binds to a site other than the active site, changing the enzyme's shape and reducing its activity. It cannot be overcome by increasing substrate concentration

    Cofactors and Coenzymes

    • Cofactors: inorganic molecules helping stabilize or assisting enzyme reaction (ex. metal ions)
    • Coenzymes: organic molecules (ex. vitamins) transferring chemical groups between molecules

    Temperature and pH Effects

    • Enzyme activity increases with temperature but decreases significantly beyond optimal temperature
    • Enzyme activity is best at optimal pH; too acidic or basic changes enzyme structure and reduces activity

    Food Energy Stages

    • Digestion: proteins, polysaccharides, and fats break down into smaller molecules (amino acids, sugars, and fatty acids)
    • Glycolysis: partially breaks down glucose, producing ATP and NADH
    • Oxidative Phosphorylation: uses energy from molecules' oxidation to form ATP using inorganic phosphate

    Glycolysis

    • Purpose: break down glucose for quick energy and production of molecules needed for further energy production
    • Inputs: glucose, 2 NAD+, 2 ADP + 2Pi
    • Outputs: 2 pyruvate, 2 NADH, 2 ATP (net gain)

    Acetyl CoA

    • Delivers energy-rich molecules to the citric acid cycle from broken-down sugars, fats, and proteins

    Citric Acid Cycle and Oxidative Phosphorylation

    • Citric Acid Cycle: produces energy carriers (NADH and FADH2) and CO2
    • Oxidative Phosphorylation: energy carriers (NADH and FADH2) power ATP production using an electron transport chain and electrochemical gradient

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    Description

    This quiz covers key concepts in energy and metabolism, including the roles of catabolism and anabolism, the different types of cellular work, and the significance of oxidation and reduction reactions. It also discusses activated carrier molecules and the function of enzymes in lowering activation energy. Test your understanding of these fundamental biological processes!

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