Anabolism and Catabolism Overview
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Questions and Answers

What is the net gain of ATP produced during glycolysis for each molecule of glucose?

  • 1 ATP
  • 2 ATP (correct)
  • 0 ATP
  • 4 ATP

    • Which phase of glycolysis involves the direct splitting of sugar?

  • Sugar cleavage (correct)
  • ATP formation
  • Sugar oxidation
  • Sugar activation

    • What happens to pyruvate when oxygen is insufficient during exercise?

  • It is stored as glycogen
  • It is converted to lactate (correct)
  • It is oxidized completely to ATP
  • It enters the citric acid cycle

    • In which part of the cell does glycolysis occur?

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

    What substance must remain available during glycolysis for the process to continue?

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

    How many steps are involved in the glycolytic pathway?

    <p>10 steps</p> Signup and view all the answers

    Which of the following describes the citric acid cycle?

    <p>It is fueled mostly by pyruvate and occurs in the mitochondrial matrix.</p> Signup and view all the answers

    What is the major product of glycolysis from one molecule of glucose?

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

    What is the first step of decarboxylation from pyruvate?

    <p>One carbon is removed as CO2.</p> Signup and view all the answers

    What is produced during the oxidation of the 2-C fragment after decarboxylation?

    <p>NADH.</p> Signup and view all the answers

    Which molecule is formed when acetate combines with coenzyme A?

    <p>Acetyl CoA.</p> Signup and view all the answers

    What does the citric acid cycle primarily produce?

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

    What role does oxygen play in the electron transport chain?

    <p>Serves as the final electron acceptor.</p> Signup and view all the answers

    What is the main outcome of chemiosmosis during oxidative phosphorylation?

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

    Which statement correctly describes the proton gradient in oxidative phosphorylation?

    <p>It has a higher concentration of protons in the intermembrane space.</p> Signup and view all the answers

    What does oxidative phosphorylation require to proceed?

    <p>Oxygen and reduced coenzymes.</p> Signup and view all the answers

    What role do cytochromes play in the electron transport chain?

    <p>They transfer electrons and contain iron.</p> Signup and view all the answers

    Which complexes in the electron transport chain accept electrons from NADH and FADH2?

    <p>Complexes I and II.</p> Signup and view all the answers

    What is the primary function of anabolism in metabolism?

    <p>To build larger molecules from smaller ones</p> Signup and view all the answers

    During which stage of metabolism do nutrients get either built into lipids or broken down into pyruvate?

    <p>Stage 2: cytoplasmic processing</p> Signup and view all the answers

    What type of reactions are involved in cellular respiration?

    <p>Oxidation-reduction reactions only</p> Signup and view all the answers

    What is the outcome of phosphorylation?

    <p>Increases molecule's activity and energy state</p> Signup and view all the answers

    Which enzyme is primarily responsible for the transfer of hydrogen atoms in redox reactions?

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

    What nutrient conversion primarily takes place in the inner mitochondrial membrane during oxidative phosphorylation?

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

    What is the primary role of coenzymes like NAD+ and FAD in oxidation-reduction reactions?

    <p>To accept electrons and become reduced</p> Signup and view all the answers

    What happens to glucose once it enters a cell?

    <p>It is converted to glucose-6-phosphate and trapped inside</p> Signup and view all the answers

    What is the net production of ATP during glycolysis?

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

    Which of the following is NOT a product of complete glucose catabolism?

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

    Which enzyme catalyzes the transfer of oxygen in redox reactions?

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

    What major energy molecule is produced by the complete breakdown of nutrients in the mitochondria?

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

    What happens to the hydrogen atoms during the oxidation of glucose?

    <p>They are accepted by oxygen to form water</p> Signup and view all the answers

    Study Notes

    Anabolism and Catabolism

    • Anabolism: builds larger molecules from smaller ones.
      • Example: protein synthesis from amino acids.
    • Catabolism: breaks down complex molecules into simpler ones.
      • Example: hydrolysis of proteins into amino acids.
    • Three major stages of processing energy-containing nutrients:
      • Stage 1: Digestion and absorption in the gastrointestinal tract.
        • Nutrients are digested into absorbable units and absorbed into the blood.
        • Nutrients are then transported to tissue cells.
      • Stage 2: Occurs in the cytoplasm.
        • Nutrients are either built into macromolecules (anabolism) or partially broken down (catabolism).
        • Glycolysis, a major catabolic pathway, breaks down nutrients into pyruvate.
      • Stage 3: Occurs in mitochondria.
        • Complete breakdown of stage 2 products, primarily converted into acetyl CoA.
        • Uses oxygen.
        • Produces carbon dioxide, water, and large amounts of ATP (adenosine triphosphate).

    Cellular Respiration

    • Cellular respiration: a group of catabolic reactions that convert chemical energy in nutrients (like glucose) into a usable form of chemical energy (ATP) for cellular work.
    • Phosphorylation: transfer of a high-energy phosphate group from ATP to another molecule.
      • Primes molecules, increases activity, produces motion, or does work.
    • Body stores energy as glycogen and triglycerides. These are broken down later to produce ATP for cellular use.

    Oxidation-Reduction Reactions and Coenzymes

    • Many reactions in cells are oxidation reactions.
      • Oxidation: the gain of oxygen or the loss of hydrogen atoms (with their electrons).
      • Oxidized substances lose electrons; reduced substances gain electrons.
      • Oxidation of glucose involves removal of hydrogen atoms (with their electrons.)
    • Oxygen is the final electron acceptor. Joining removed hydrogen atoms to O2 forms water (H₂O).
    • Dehydrogenases: catalyze the removal of hydrogen atoms.
    • Oxidases: catalyze the transfer of oxygen.
      • Many redox enzymes require B vitamins as coenzymes. The B vitamin coenzyme can accept hydrogen atoms and electrons, becoming reduced when a substrate is oxidized.

    Two Important Coenzymes in the Oxidative Pathway

    • Nicotinamide adenine dinucleotide (NAD+)
    • Flavin adenine dinucleotide (FAD)
      • Example: FAD is reduced to FADH2 as succinate is oxidized to fumarate.

    ATP Synthesis

    • Two mechanisms capture energy released during cellular respiration as ATP.
      • Substrate-level phosphorylation: Direct transfer of a high-energy phosphate group from a substrate to ADP.
        • Occurs in glycolysis (twice), and once in the Krebs cycle (in mitochondria).
      • Oxidative phosphorylation: More complex, produces most ATP.
        • Carried out by inner mitochondrial membrane proteins in two steps.
          • Electron transport: Transfers electrons to create a proton gradient.
          • Chemiosmosis: Uses the energy of the proton gradient to synthesize ATP. - H+ (protons) diffuses across inner mitochondrial membrane through ATP synthase protein. - Synthesizes ATP from ADP.

    Carbohydrate Metabolism

    • Food carbohydrates are converted into glucose.
    • Glucose enters cells via glucose transporters, process enhanced by insulin.
    • Glucose is immediately phosphorylated to glucose-6-phosphate within cells.
    • Only specific cells (intestine, kidney, liver) have enzymes necessary to reverse the reaction and release glucose.
    • Intracellular glucose concentration is kept low to ensure continued glucose uptake.

    Oxidation of Glucose

    • Glucose is catabolized (broken down) through glycolysis, citric acid cycle, and oxidative phosphorylation.
    • Equation for complete glucose catabolism: C₆H₁₂O₆ + 6O₂ → 6H₂O + 6CO₂ + 32 ATP + heat

    Glycolysis (Glycolytic Pathway)

    • Occurs in the cytosol; glycolysis involves 10 chemical steps to convert glucose to two pyruvate molecules.
    • It is an anaerobic process, which means it does not require oxygen to proceed.
    • Three major phases:
      • Phase 1: Sugar activation: glucose first phosphorylated to fructose-1,6-bisphosphate
      • Phase 2: Sugar cleavage: 6-carbon sugars split into two 3-carbon fragments
      • Phase 3: Sugar oxidation and ATP formation: 3-carbon fragments are oxidized and 4 ATP molecules are formed

    Oxidation of Glucose: Glycolysis (Continued)

    • NAD+ is reduced to NADH+H+ to accept electrons from glucose.
    • When oxygen is present, pyruvate is oxidized aerobically (in the citric acid cycle, etc.).
    • If oxygen is not available, pyruvate is reduced to lactate (lactic acid). The lactate can enter the blood to be transported to the liver where it will be oxidized to pyruvate if oxygen becomes available. In this way the NAD+ is regenerated and can continue to participate in glycolysis if needed.

    Citric Acid Cycle (Krebs Cycle)

    • Next stage of glucose oxidation
    • Occurs in the mitochondrial matrix,
    • Fueled primarily by pyruvate (from glycolysis) and fatty acids.

    Citric Acid Cycle (continued)

    • Transitional phase: 3-step conversion of pyruvate to Acetyl CoA
      • Decarboxylation: loss of a carbon to form CO2.
      • Oxidation: the remaining 2-carbon fragment oxidized
      • Formation of acetyl CoA: acetate + coenzyme A combine to yield acetyl CoA

    Oxidation of Glucose: Citric Acid (Krebs) Cycle summary

    • Two molecules of CO2 are produced.
    • Four reduced coenzymes (3 NADH and 1 FADH₂) are produced, carrying high-energy electrons.
    • One molecule of ATP (or GTP) is produced.

    Oxidative Phosphorylation

    • ETCs only pathway that directly uses oxygen.
    • The citric acid cycle provides substrates for the electron transport chain (ETC).
    • The coupled pathways are aerobic, requiring oxygen.
    • NADH + H+ and FADH transfer electrons from glycolysis and the Krebs cycle to the electron transport chain.
    • Chemiosmosis uses the energy released during electron transport to form ATP.
      • Electron transport chain embedded in inner mitochondrial membrane
      • Uses proteins (like flavin, iron-containing complexes) to facilitate electron transport, and to generate proton gradient to drive ATP synthesis.

    Oxidative phosphorylation summary

    • The electron transport chain (ETC) generates a proton gradient across the inner mitochondrial membrane.
    • ATP synthase enzymes use the energy of the gradient to generate ATP.

    Energy Harvested from the Electron Transport Chain

    • Energy is harvested in increments as electrons move from one protein complex to another in the chain.
    • Energy is released at each step, some is lost as heat, and some used to pump protons, creating a proton gradient.

    Oxidative Phosphorylation cont.

    • Phase 2: Chemiosmosis
      • Uses energy of proton gradient.
      • H+ move back across membrane into mitochondrial matrix through ATP synthesis complex (complex V)
      • Protein complex V rotates, causing ADP to attach to phosphate group to form ATP

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    Anabolism and Catabolism PDF

    Description

    Explore the processes of anabolism and catabolism, focusing on how larger molecules are constructed from smaller ones and how complex molecules are broken down. This quiz covers the three major stages of processing energy-containing nutrients, from digestion to the final breakdown in mitochondria. Test your understanding of these essential metabolic pathways.

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