Metabolism Chapter Overview
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Questions and Answers

What is produced from the oxidative decarboxylation of pyruvate inside the mitochondria?

  • 3-phosphoglycerate and ATP
  • Lactate and CO2
  • Acetyl-CoA and NADH (correct)
  • ATP and FADH2

    • Where does the Krebs cycle occur?

  • Inner mitochondrial membrane
  • Cytoplasm
  • Mitochondrial matrix (correct)
  • Outer mitochondrial membrane

    • Which process primarily generates ATP in the presence of oxygen?

  • Substrate-level phosphorylation
  • Fermentation
  • Glycolysis
  • Oxidative phosphorylation (correct)

    • What role does NADH play in the electron transport chain?

    <p>It serves as an electron carrier</p> Signup and view all the answers

    Which substance is produced during the Krebs cycle along with NADH?

    <p>CO2 and FADH2</p> Signup and view all the answers

    What is the end product of glycolysis?

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

    How does the inner mitochondrial membrane contribute to ATP synthesis?

    <p>It is selectively permeable and hosts the electron transport chain</p> Signup and view all the answers

    What is the main source of glucose in gluconeogenesis?

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

    Which of the following is NOT a function of NADH in cellular respiration?

    <p>To participate in the Krebs cycle directly</p> Signup and view all the answers

    Which of the following processes primarily occurs in the liver?

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

    What is the role of gluconeogenesis in energy metabolism?

    <p>To form glucose from non-carbohydrate sources</p> Signup and view all the answers

    During which condition does muscle metabolism switch to anaerobic glycolysis?

    <p>During vigorous exercise</p> Signup and view all the answers

    What are ketone bodies produced from?

    <p>Fatty acid oxidation</p> Signup and view all the answers

    What is the significance of the Cori cycle?

    <p>It converts lactate back to glucose</p> Signup and view all the answers

    Which transporter is primarily responsible for insulin-sensitive glucose uptake in muscle and adipose tissues?

    <p>GLUT-4</p> Signup and view all the answers

    What is the primary role of glucose-6-phosphate in glycolysis?

    <p>Facilitates conversion to fructose-1,6-bis-P</p> Signup and view all the answers

    Which of the following is NOT a substrate for gluconeogenesis?

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

    Which metabolic pathway is responsible for producing ATP from the breakdown of fatty acids?

    <p>β-oxidation</p> Signup and view all the answers

    What type of energy is required for gluconeogenesis?

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

    What is the physiological response when blood glucose levels increase?

    <p>Pancreas secretes insulin</p> Signup and view all the answers

    Which of the following statements about the urea cycle is correct?

    <p>It occurs exclusively in the liver.</p> Signup and view all the answers

    Which enzyme is primarily responsible for the conversion of fructose-6-phosphate to fructose-1,6-bis-phosphate in glycolysis?

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

    What is the primary role of the electron transport chain in cellular metabolism?

    <p>Production of ATP via oxidative phosphorylation</p> Signup and view all the answers

    Which glucose transporter has the highest affinity for glucose?

    <p>GLUT-1</p> Signup and view all the answers

    What is the primary purpose of deamination in amino acid metabolism?

    <p>To convert amino acids into glucose or lipids</p> Signup and view all the answers

    Which compound is produced during the urea cycle and released into the bloodstream?

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

    Which amino acid is NOT an energy source for most tissues?

    <p>Amino acids</p> Signup and view all the answers

    What is the primary nitrogen-containing compound excreted through the kidneys?

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

    Which statement about fatty acid metabolism in tissues is accurate?

    <p>Fatty acids are minimally utilized by most tissues.</p> Signup and view all the answers

    Which amino acid is considered an essential one that must be obtained through diet?

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

    What process allows amino acids to enter the Krebs cycle?

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

    Which of the following amino acids is primarily involved in the urea cycle?

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

    What is the primary role of NADH in the tricarboxylic acid cycle?

    <p>To donate electrons to the electron transport chain</p> Signup and view all the answers

    In the context of β-oxidation of fatty acids, what is produced as a byproduct?

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

    Which molecule is formed when acetyl-CoA enters the tricarboxylic acid cycle?

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

    What is a major purpose of the tricarboxylic acid cycle?

    <p>To produce reducing equivalents such as NADH and FADH2</p> Signup and view all the answers

    Which enzyme is responsible for the conversion of succinyl-CoA to succinate, producing GTP in the process?

    <p>Succinyl-CoA synthetase</p> Signup and view all the answers

    What compound is regenerated in the final steps of the tricarboxylic acid cycle?

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

    Which type of molecule is primarily oxidized during β-oxidation?

    <p>Fatty acids</p> Signup and view all the answers

    What is the net gain of NADH and FADH2 during one cycle of β-oxidation of a saturated fatty acid?

    <p>One of each</p> Signup and view all the answers

    Study Notes

    Learning Outcomes

    • Glycolysis: Breakdown of glucose to pyruvate
    • Oxidative decarboxylation: Conversion of pyruvate to acetyl-CoA
    • Krebs cycle: Oxidation of acetyl-CoA to produce NADH and FADH2
    • β-oxidation of fatty acids: Breakdown of fatty acids to acetyl-CoA
    • Electron transport chain and ATP synthesis: Production of ATP using the energy from electrons
    • Energy storage and utilisation of stores: Processes for storing and using glucose, fatty acids, and glycogen
    • Gluconeogenesis: Synthesis of glucose from non-carbohydrate sources
    • Urea cycle: Breakdown of ammonia to urea
    • Roles of different organs: Liver, kidneys, and muscle in metabolism

    Metabolic Response to Food

    • Increased blood glucose stimulates insulin secretion from pancreatic beta cells
    • Insulin promotes glucose uptake by cells

    Glucose Transporters

    • GLUT-1: Basal glucose uptake in RBCs, brain, and most tissues (high affinity)
    • GLUT-2: Glucose sensing in liver and pancreatic beta cells (low affinity)
    • GLUT-3: Glucose uptake in brain, intestine, and placenta
    • GLUT-4: Insulin-sensitive glucose uptake in muscle and adipose tissue
    • GLUT-5: Fructose uptake in the intestine
    • SGLT-1: Active transport of glucose and sodium in the intestine and kidney

    Glycolysis

    • Breakdown of glucose to pyruvate
    • Occurs in the cytoplasm
    • Produces 2 ATP, 2 pyruvate, and 2 NADH

    Mitochondria – Oxidative Phosphorylation

    • Most ATP production takes place in the mitochondria
    • Krebs cycle occurs in the mitochondrial matrix
    • Electron transport chain is located on the inner mitochondrial membrane

    Oxidative Decarboxylation

    • Conversion of pyruvate to acetyl-CoA
    • Occurs in the mitochondria
    • Produces NADH

    Oxidative Phosphorylation

    • Electron transport chain utilizes NADH and FADH2 to produce ATP
    • Acetyl-CoA is used in the Krebs cycle to generate NADH and FADH2

    Krebs Cycle

    • Also known as the citric acid cycle or tricarboxylic acid cycle
    • Oxidation of acetyl-CoA to produce NADH and FADH2

    β-oxidation of Fatty Acids

    • Breakdown of fatty acids to acetyl-CoA
    • Produces FADH2 and NADH

    Production of NADH and FADH2

    • Triglycerides are broken down by lipolysis, generating free fatty acids and glycerol
    • β-oxidation of fatty acids produces FADH2 and NADH
    • Glycolysis produces NADH

    Utilisation of Energy Stores

    • Glucose stored as glycogen in the liver and skeletal muscle
    • Glycogenolysis breaks down glycogen to glucose-6-P
    • Gluconeogenesis converts glycerol, lactate, and amino acids to glucose
    • Triglycerides are broken down by lipolysis, producing fatty acids and glycerol
    • β-oxidation of fatty acids produces acetyl-CoA
    • Ketone bodies are produced from fatty acids in the liver

    Gluconeogenesis

    • Synthesis of glucose from non-carbohydrate sources
    • Occurs mainly in the liver
    • Uses glycerol, lactate, and amino acids as substrates

    The Cori Cycle

    • Lactate produced during anaerobic glycolysis is transported to the liver
    • Gluconeogenesis converts lactate back to glucose
    • Requires energy to regenerate glucose

    Biosynthetic Roles of the Krebs Cycle

    • Precursors for amino acid biosynthesis from intermediates in the Krebs cycle

    Amino Acid Metabolism

    • Amino acids require deamination (removal of the amino group) before being used for glucose/lipid synthesis
    • Urea is produced in the liver via the urea cycle

    Urea Cycle and Krebs Cycle

    • Amino acids are broken down into urea via the urea cycle
    • Intermediates from the urea cycle can be used in the Krebs cycle

    Tissue Variations in Energy Source

    • Glucose is the main energy source for most tissues, essential for brain and RBCs
    • Fatty acids are used by most tissues, except for neurons
    • Ketones can be used by most tissues

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    Description

    This quiz covers key topics in metabolism, including glycolysis, the Krebs cycle, and the urea cycle. It highlights the roles of various organs in metabolism and examines glucose transporters. Test your understanding of how energy is produced and utilized in the body.

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