Energy and Metabolism
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Questions and Answers

What is the outcome of one complete cycle of beta-oxidation of fatty acids?

  • 1 NADH and 3 ATP
  • 1 NADH and 2 FADH2
  • 1 NADH and 1 FADH2 (correct)
  • 1 NADH, 1 FADH2, and 2 ATP

    • Which enzyme is responsible for replacing CoA with carnitine for fatty acid transport into mitochondria?

  • Acylcarnitine transferase II
  • Acyl-CoA synthetase
  • Carnitine palmitoyltransferase I (correct)
  • Carnitine acyltransferase

    • What inhibits the function of acylcarnitine transferase I?

  • Malonyl CoA (correct)
  • Acetyl CoA
  • Fatty acids
  • Citrate

    • The total ATP yield from the complete oxidation of lauric acid (C12) is?

    <p>95 ATP (D)</p> Signup and view all the answers

    When proteins are catabolized, the first step involves?

    <p>Deamination of amino acids (D)</p> Signup and view all the answers

    Acetyl CoA derived from fatty acid oxidation can enter which metabolic cycle?

    <p>Citric acid cycle (Krebs cycle) (D)</p> Signup and view all the answers

    How many oxidation cycles occur for a fatty acid with 14 carbons?

    <p>6 (C)</p> Signup and view all the answers

    What does the catabolism of alanine directly produce?

    <p>Pyruvate (C)</p> Signup and view all the answers

    What is the role of ATP in the activation of a fatty acid before oxidation?

    <p>2 ATP are consumed (A)</p> Signup and view all the answers

    What molecule is produced from the deamination of amino acids during protein catabolism?

    <p>Ammonium ion (A)</p> Signup and view all the answers

    What is the main function of phospho-fructokinase in glycolysis?

    <p>To phosphorylate fructose-6-phosphate (C)</p> Signup and view all the answers

    Which of the following occurs during the oxidation and ATP formation phase of glycolysis?

    <p>ADP captures terminal phosphates to form ATP (B)</p> Signup and view all the answers

    In the absence of sufficient oxygen, what does pyruvic acid get converted to?

    <p>Lactic acid (B)</p> Signup and view all the answers

    What does the Krebs cycle primarily produce for each acetyl CoA molecule processed?

    <p>Three molecules of NADH and one FADH2 (D)</p> Signup and view all the answers

    Which step in the conversion of pyruvic acid to acetyl CoA involves the removal of a carbon atom?

    <p>Decarboxylation (A)</p> Signup and view all the answers

    What creates the proton gradient across the inner mitochondrial membrane during oxidative phosphorylation?

    <p>Transfer of electrons down the chain (C)</p> Signup and view all the answers

    In glycolysis, what is the initial substrate that is activated?

    <p>Glucose (D)</p> Signup and view all the answers

    During ATP synthesis in oxidative phosphorylation, what process allows protons to move back into the mitochondrial matrix?

    <p>Diffusion through ATP synthase (A)</p> Signup and view all the answers

    How many molecules of acetyl CoA are produced from one molecule of glucose during glycolysis?

    <p>Two (B)</p> Signup and view all the answers

    Which of the following statements regarding the Krebs cycle is true?

    <p>It generates NADH, FADH2, and CO2 (D)</p> Signup and view all the answers

    What is the primary function of glycolysis in glucose metabolism?

    <p>To break down glucose into pyruvate (C)</p> Signup and view all the answers

    Which of the following correctly describes catabolism?

    <p>It releases energy and breaks down larger molecules. (A)</p> Signup and view all the answers

    What is the role of coenzymes like NAD+ and FAD in metabolism?

    <p>They act as hydrogen or electron acceptors. (C)</p> Signup and view all the answers

    Which reaction represents the overall oxidation of glucose?

    <p>C6H12O6 + 6O2 → 6CO2 + 6H2O + 36ATP + heat (D)</p> Signup and view all the answers

    In metabolism, what does the term 'endergonic' refer to?

    <p>Reactions that require energy (A)</p> Signup and view all the answers

    What happens to energy during the process of anabolism?

    <p>Energy is stored and used to create complex molecules. (A)</p> Signup and view all the answers

    Which statement is true regarding the phases of metabolism?

    <p>Catabolism liberates energy while anabolism requires energy. (B)</p> Signup and view all the answers

    During glycolysis, how many ATP molecules are produced from one glucose molecule?

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

    Flashcards

    Metabolism

    The sum of catabolism and anabolism

    Catabolism

    The breakdown of molecules, releasing energy (exergonic).

    Anabolism

    The synthesis of molecules, requiring energy (endergonic).

    Energy Currency

    ATP, the molecule that cells use to store and transfer energy.

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    Glycolysis

    The first stage of glucose breakdown, doesn't need oxygen.

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    ATP

    Adenosine triphosphate; a high-energy molecule.

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    Glucose Breakdown

    The oxidation of C6H12O6 into 6H2O, 6CO2, and ATP + heat.

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    Metabolic Stages

    Catabolism and anabolism, opposite processes in pathways.

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    Rate-limiting step of glycolysis

    The phosphorylation of fructose-6-phosphate by phospho-fructokinase

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    Pyruvic acid fate (aerobic)

    Converts to acetyl CoA, entering the Krebs cycle.

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    Pyruvic Acid (anaerobic)

    Reduced to lactic acid when oxygen is insufficient.

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    Glycolysis Phase 1

    Activation phase, glucose is converted to Fructose-1,6-diphosphate using 2 ATP molecules

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    Krebs Cycle Preparatory step

    Pyruvic acid converted to acetyl CoA (A-CoA).

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    Krebs Cycle (Citric Acid Cycle)

    Eight-step cycle where A-CoA is decarboxylated and oxidized to release energy in the form of NADH, FADH2, CO2 and ATP.

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    Oxidative Phosphorylation

    A process in the mitochondria where electrons are passed down a chain to form a proton gradient, used to make ATP.

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    Cellular Respiration Summary

    The overall process of breaking down glucose to release energy in the form of ATP. Consumes glucose and oxygen, releasing carbon dioxide and water.

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    Acetyl CoA

    Molecule that carries the 2-carbon acetyl group into the Krebs Cycle

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    Beta-oxidation of fatty acids

    A metabolic process breaking down fatty acids into acetyl CoA, producing NADH and FADH2 for energy.

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    Carnitine shuttle

    Process transporting fatty acyl-CoA into the mitochondria for beta-oxidation.

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    Protein catabolism

    The breakdown of proteins into amino acids.

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    Deamination

    Removal of the amino group from an amino acid during catabolism.

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    Urea Cycle

    Metabolic pathway that converts ammonia to urea, removing it from the body.

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    Amino Acid Catabolism

    The breakdown of amino acids into molecules usable by the body.

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    ATP Production (Fatty Acids)

    Number of ATP molecules generated from oxidizing a fatty acid dependent on the number of carbons.

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    Malonyl CoA

    Inhibits the transport of fatty acids into the mitochondria when fatty acid synthesis is active.

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    Liver (Protein Degradation)

    Main site of protein degradation in mammals.

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    Study Notes

    Energy and Metabolism

    • Metabolism is the sum of catabolic and anabolic chemical processes.
    • Catabolism releases energy (exergonic), anabolism takes up energy (endergonic).
    • Proteins break down into amino acids.
    • Carbohydrates break down into glucose, fructose, and galactose.
    • Fats and lipids break down into fatty acids and glycerol.
    • Glycogen breaks down into glucose-6-phosphate.
    • Glycolysis converts glucose into pyruvic acid.
    • Gluconeogenesis converts noncarbohydrate precursors into glucose.
    • Lactic acid is formed during anaerobic respiration.
    • Citric acid cycle is a series of reactions where acetyl CoA is broken down.
    • Electron transport chain produces a large amount of ATP.
    • Synthesis of larger molecules (anabolism) requires energy.
    • Proteins are created from amino acids.
    • Carbohydrates are synthesized into starch.

    Common Intermediate in Metabolism

    • Several molecules converge into a common intermediate, acetate (acetyl-CoA).
    • This intermediate fuels various anabolic pathways.
    • Examples of end products include steroids, hormones, and carotenoids.

    Two Phases of Metabolism

    • Catabolism occurs through degradative and oxidative, converging pathways.
    • Anabolism uses biosynthetic and reductive pathways, diverging in product synthesis.

    Energy Currency in Metabolism

    • ATP is the energy currency of the cell.
    • ADP and AMP are related to energy storage.
    • Coenzymes such as NAD+ and FAD accept hydrogen or electrons, which are used in ATP production.

    Cellular Respiration: Overview

    • Glucose is oxidized to yield energy in the form of ATP.
    • The process occurs in three main stages: glycolysis, transition reaction, and citric acid cycle followed by the electron transport chain.
    • Glycolysis produces a net gain of two ATPs.
    • The transition reaction converts pyruvate into acetyl CoA.
    • The citric acid cycle produces CO2 and electron carriers.
    • The electron transport chain generates a large amount of ATP from electrons.
    • The overall reaction is C6H12O6 + 6O2 → 6H2O + 6CO2 + 36 ATP + heat (AG = -686 kcal/mol).

    Glycolysis

    • The first stage of glucose catabolism.
    • No oxygen required.
    • Occurs in the cytoplasm.
    • Converts 6C glucose into two 3C pyruvates.
    • Produces a small amount of energy (2 ATP).
    • Pathway regulated according to cellular needs.

    Fate of Pyruvic Acid

    • Pyruvic acid from glycolysis is converted to acetyl coenzyme A for the Krebs cycle.
    • Occurs in three steps: decarboxylation, oxidation, and formation of acetyl CoA.

    Krebs Cycle

    • An eight-step cycle that oxidizes acetic acid, generates three NADH+H+ and FADH2, and two CO2 molecules.
    • Produces one ATP molecule.
    • For each glucose molecule entering, two molecules of acetyl CoA enter the Krebs cycle.

    Oxidative Phosphorylation

    • Hydrogen ions are pumped across the inner mitochondrial membrane to create a proton gradient.
    • Electrons are passed along the electron transport chain to oxygen.
    • Diffusion of hydrogen ions back across the membrane via ATP synthase releases energy for ATP production.

    ATP Production

    • Total net ATP yield: 36 or 38 ATP molecules per glucose molecule (theoretical).
    • Exact number can vary depending on the cell type.

    Lipid Catabolism

    • Lipids are broken down into fatty acids and glycerol.
    • Fatty acids undergo B-oxidation to produce acetyl CoA.
    • Glycerol enters glycolysis.
    • Acetyl CoA is a crucial fuel for the Krebs cycle, which produces ATP.

    Protein Catabolism

    • Proteins are broken down into amino acids by hydrolysis.
    • The amino group is removed via deamination, producing ammonia.
    • The remaining molecules enter the Krebs cycle for energy generation.
    • The ammonia is converted to urea for excretion.

    Cori Cycle

    • The liver and muscles work together in the Cori cycle to recycle lactic acid.
    • Lactic acid produced by muscles during anaerobic respiration is transported to the liver, where it is converted back into glucose.
    • This glucose is then transported back to the muscles for use in energy production.

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    Description

    This quiz explores the key concepts of energy and metabolism, including the differences between catabolism and anabolism, glycolysis, and the citric acid cycle. Understanding these metabolic pathways is crucial for comprehending how living organisms convert nutrients into energy and synthesize necessary molecules. Test your knowledge on metabolic processes and their significance in biology.

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