Biochemistry: Deamination, Urea Cycle, and Transamination Quiz
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Questions and Answers

Why should all metabolic pathways be regulated?

  • To ensure energy is efficiently utilized
  • To increase the rate of metabolic reactions
  • To maintain cellular homeostasis (correct)
  • To prevent the buildup of toxic intermediates

    • Why is the hexokinase step not the committed step in glycolysis?

  • It is reversible (correct)
  • It occurs after the phosphofructokinase step
  • It does not require ATP
  • It is not an early step in the glycolysis pathway

    • Why is fructose 1,6-bisphosphate converted to glyceraldehyde-phosphate and dihydroxyacetone phosphate?

  • To form ATP molecules
  • To generate NADH for energy production
  • To increase the pH of the cytoplasm
  • To yield intermediates for further glycolytic reactions (correct)

    • Why is glucose frequently administered intravenously to patients?

    <p>To maintain stable blood sugar levels</p> Signup and view all the answers

    What is the role of Gibbs free energy in biochemical reactions?

    <p>Determining the direction of spontaneous reactions</p> Signup and view all the answers

    How does entropy impact biological systems?

    <p>It influences the spontaneity of chemical reactions</p> Signup and view all the answers

    What is the role of the pyridoxal-5-phosphate cofactor in the deamination process of amino acids?

    <p>Facilitating the removal of the amino group</p> Signup and view all the answers

    What is the enzyme, coenzyme, and vitamin required for transamination?

    <p>Transaminase, NADPH, Vitamin B6</p> Signup and view all the answers

    Why are people with Glucose-6-phosphate dehydrogenase (G6PD) deficiency at risk of haemolytic anemia?

    <p>Reduced antioxidant capacity</p> Signup and view all the answers

    What does the pentose phosphate pathway tailor to meet the body's specific need of NADPH?

    <p>Generation of ribose-5-phosphate</p> Signup and view all the answers

    In the citric acid cycle, which enzyme catalyzes the first reaction?

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

    How is the citric acid cycle regulated?

    <p>Inhibition by high levels of NADH and ATP</p> Signup and view all the answers

    What is the final product generated directly by the conversion of Succinyl CoA in the Krebs Cycle?

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

    Which molecule is oxidized to produce FADH2 in the Krebs Cycle?

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

    How many molecules of NADH are produced from the Krebs Cycle after one turn?

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

    Who was awarded the Nobel Prize in Physiology or Medicine for his work on proposing the Krebs Cycle?

    <p>Sir Hans Adolf Krebs</p> Signup and view all the answers

    What is the key compound identified by Fritz Lipmann and Nathan Kaplan essential for the operation of the Krebs Cycle?

    <p>Coenzyme A</p> Signup and view all the answers

    Where does the Krebs Cycle take place in most living organisms?

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

    What is the initial step that initiates the Krebs Cycle?

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

    Which compound is formed by the oxidation of isocitrate in the Krebs Cycle?

    <p>Alpha-ketoglutarate</p> Signup and view all the answers

    What is the final product after the conversion of alpha-ketoglutarate in the Krebs Cycle?

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

    Which of the following best describes the Krebs Cycle's pathway?

    <p>Closed loop where the last part regenerates the compound used first</p> Signup and view all the answers

    What is the role of oxaloacetate in the Krebs Cycle?

    <p>Regeneration of the compound used in the first step</p> Signup and view all the answers

    Which part of a cell does the Krebs Cycle mainly take place in?

    <p>&quot;Mitochondria&quot;</p> Signup and view all the answers

    Study Notes

    Biochemistry Exam Questions

    • The exam consists of 4 questions, with a total of 2 hours to complete.
    • Question 1 is about biochemistry, with 5 parts (a, b, c, d, and e).
    • Part a asks to draw a reaction mechanism for converting fructose 1,6-bisphosphate to glyceraldehyde 3-phosphate and dihydroxyacetone phosphate.
    • Part b explains the terms Gibbs free energy, entropy, and their significance in metabolism.
    • Part c discusses why catabolic and anabolic pathways differ, and why metabolic pathways should have a committed step.

    Deamination and Urea Cycle

    • Deamination is the process of removing an amino group from an amino acid.
    • The pyridoxal-5-phosphate cofactor plays a crucial role in the deamination process.
    • The enzyme, coenzyme, and vitamin required for transamination are not specified.
    • The urea cycle is regulated and linked to the citric acid cycle.
    • The urea cycle is called a "cycle" because it involves a series of reactions that regenerate the initial reactant.

    Pentose Phosphate Pathway

    • The pentose phosphate pathway is tailored to meet the body's specific need for NADPH but not ribose-5-phosphate.
    • The pathway is essential for generating NADPH, which is necessary for reducing oxidized glutathione.
    • People with glucose-6-phosphate dehydrogenase (G6PD) deficiency are at risk of hemolytic anemia due to their inability to regenerate NADPH.
    • The pentose phosphate pathway has five importance: generating NADPH, producing ribose-5-phosphate, and maintaining the balance of reactive oxygen species.

    Citric Acid Cycle

    • The citric acid cycle, also known as the Krebs cycle, is a crucial process in cellular respiration.
    • The cycle is a series of reactions that takes place in the mitochondria of most living organisms.
    • The cycle is initiated when acetyl CoA reacts with oxaloacetate to form citrate and release coenzyme A (CoA-SH).
    • The cycle consists of 7 steps, each catalyzed by a specific enzyme.
    • The cycle produces energy through the formation of ATP, NADH, and FADH2.
    • The energy is generated through a series of redox reactions, where electrons are transferred from one substance to another.

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    Description

    Test your knowledge on biochemistry topics such as deamination of amino acids, role of pyridoxal-5-phosphate, regulation of urea cycle, links to citric acid cycle, and enzymes/coenzymes involved in transamination. Explore key concepts in metabolic pathways.

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