Biochem Lecture 1 Review
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Questions and Answers

What is the primary location where glycogenesis occurs?

  • Heart
  • Skeletal muscle
  • Liver (correct)
  • Adipose tissue
  • Which substrate is primarily used for gluconeogenesis?

  • Lactate (correct)
  • Fatty acids
  • Amino acids (correct)
  • Glucose
  • What is the primary product of glycolysis?

  • Lactate
  • Pyruvate (correct)
  • Glucose
  • Fructose
  • Which enzyme initiates the first step of glycogen breakdown?

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

    Which cycle involves the conversion of lactate back into glucose?

    <p>Cori Cycle</p> Signup and view all the answers

    What is the role of glycogenin in glycogen synthesis?

    <p>It serves as a primer for glycogen synthesis.</p> Signup and view all the answers

    Which process converts glucose into pyruvate?

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

    How is glycogen metabolism primarily regulated?

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

    What is the primary function of the pentose phosphate pathway in erythrocytes?

    <p>To supply NADPH for maintaining reduced glutathione</p> Signup and view all the answers

    Which cell types are known to have the highest levels of pentose phosphate pathway enzymes?

    <p>Liver and adipose tissue cells</p> Signup and view all the answers

    What is the consequence of the inability to maintain reduced glutathione in erythrocytes?

    <p>Increased generation of reactive oxygen species</p> Signup and view all the answers

    How do neutrophils and macrophages utilize NADPH generated from the pentose phosphate pathway?

    <p>To produce reactive oxygen species for immune response</p> Signup and view all the answers

    What histological feature is associated with the oxidation of hemoglobin due to increased peroxide accumulation in erythrocytes?

    <p>Presence of Heinz bodies</p> Signup and view all the answers

    What is the mnemonic used to remember the nine essential amino acids?

    <p>PVT TIM HiLL</p> Signup and view all the answers

    Which of the following is NOT classified as an essential amino acid?

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

    What structural feature is common to all amino acids?

    <p>An amino group</p> Signup and view all the answers

    When amino acids undergo degradation, what primarily happens to them?

    <p>They are broken down into their constituent molecules.</p> Signup and view all the answers

    How are amino acids related to the Krebs cycle?

    <p>They can be converted into intermediates that enter the Krebs cycle.</p> Signup and view all the answers

    Which essential amino acid is represented by the letter 'H' in the mnemonic?

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

    What type of bond is primarily responsible for the formation of proteins from amino acids?

    <p>Peptide bonds</p> Signup and view all the answers

    Which of the following amino acids is classified as a branched-chain amino acid?

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

    What ketone bodies are produced when beta oxidation surpasses the capacity of the Krebs cycle?

    <p>Acetoacetate, beta hydroxybutyrate, acetone</p> Signup and view all the answers

    Under which conditions are ketone bodies most likely to be released into the bloodstream?

    <p>Prolonged strenuous exercise</p> Signup and view all the answers

    Which tissue is primarily responsible for metabolizing ketone bodies back into acetyl-CoA?

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

    What is the primary implication of accelerated beta oxidation in the body?

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

    Which of the following scenarios would NOT typically lead to increased beta oxidation?

    <p>Excessive carbohydrate consumption</p> Signup and view all the answers

    Which of the following statements about the relationship between beta oxidation and ketone bodies is true?

    <p>Beta oxidation produces ketone bodies when the Krebs cycle is less active.</p> Signup and view all the answers

    In uncontrolled diabetes, which metabolic pathway becomes overwhelmed, leading to high levels of ketone bodies?

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

    What is a primary characteristic of ketone bodies during prolonged fasting?

    <p>They provide an alternative energy source.</p> Signup and view all the answers

    Which monosaccharide is primarily known for its role as a primary energy source in the body?

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

    What is a characteristic feature of saponifiable lipids?

    <p>They can yield salts of fatty acids when hydrolyzed.</p> Signup and view all the answers

    Which of the following vitamins is classified as fat-soluble?

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

    What is one consequence of vitamin deficiency related to water-soluble vitamins?

    <p>Weakened immune response</p> Signup and view all the answers

    What role do fatty acids play in cell function?

    <p>They are building blocks for cell membranes.</p> Signup and view all the answers

    Which mineral is necessary for the proper functioning of muscles and nerves?

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

    What process describes the breakdown of nucleic acids?

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

    Which statement correctly describes the function of enzymes?

    <p>Enzymes facilitate chemical reactions by lowering the activation energy.</p> Signup and view all the answers

    Study Notes

    Amino Acid Structure and Function

    • Amino acids are organic compounds composed of an amino group, a carboxyl group, and a unique side chain (R group) that determines their properties.
    • Peptides and proteins are formed through peptide bonds, linking amino acids via condensation reactions.

    Essential Amino Acids

    • Essential amino acids cannot be synthesized by the body and must be obtained from diet.
    • Mnemonic ''PVT TIM HiLL'' helps recall the nine essential amino acids:
      • P: phenylalanine
      • V: valine
      • T: tryptophan
      • T: threonine
      • I: isoleucine
      • M: methionine
      • H: histidine
      • L: leucine
      • L: lysine

    Amino Acid Degradation

    • Degradation involves the removal of amino groups to convert amino acids into intermediates like pyruvate, acetyl-CoA, or Krebs cycle intermediates.

    Conversion of Amino Acids

    • Amino acids can serve as substrates for the Krebs cycle, contributing to energy production and biosynthesis of key molecules.

    Protein Structure and Classification

    • Proteins are classified by structure: primary (sequence of amino acids), secondary (alpha helices and beta sheets), tertiary (3D shape), and quaternary (multiple polypeptides).

    Carbohydrates

    • Monosaccharides such as glucose, fructose, galactose, and ribose are fundamental for energy storage and metabolism.

    Lipids: Classification, Structure, and Function

    • Lipids include triglycerides, phospholipids, and steroids; they are essential for cell membranes, energy storage, and signaling.
    • Saponifiable lipids can be hydrolyzed to yield fatty acid salts, while nonsaponifiable lipids cannot undergo this reaction.

    Water-Soluble Vitamins

    • Important water-soluble vitamins include B vitamins and vitamin C; deficiency leads to conditions such as scurvy and beriberi.

    Fat-Soluble Vitamins

    • Fat-soluble vitamins A, D, E, and K are absorbed with dietary fat; deficiencies can lead to various disorders affecting vision, bone health, and blood clotting.

    Function of Minerals

    • Key minerals include calcium (bone health), magnesium (energy production), sodium (fluid balance), phosphate (energy transfer), copper (iron metabolism), and potassium (muscle function).

    Enzyme Function

    • Enzymes are biological catalysts that accelerate biochemical reactions, lowering activation energy and increasing reaction rates.

    Nucleic Acid Formation and Degradation

    • DNA and RNA are formed through nucleotides; degradation involves hydrolysis, resulting in the release of nucleotides for recycling.

    Glycolysis

    • Glycolysis occurs in the cytoplasm, converting glucose into pyruvate with a net gain of ATP, and is regulated by key enzymes such as phosphofructokinase.

    Gluconeogenesis

    • The process of gluconeogenesis generates glucose from non-carbohydrate substrates, occurring primarily in the liver and regulated by hormones like glucagon.

    Lactate and the Cori Cycle

    • The Cori cycle converts lactate produced in anaerobic conditions back into glucose in the liver, facilitating continuous energy supply during intense exercise.

    Glycogen Metabolism

    • Glycogen is synthesized by adding glucose to glycogenin and broken down by glycogen phosphorylase; it is primarily stored in the liver and muscle, and helps regulate blood glucose levels.

    Pentose Phosphate Pathway (PPP)

    • The PPP generates NADPH for biosynthetic reactions and ribose-5-phosphate for nucleotide synthesis; it is active in tissues requiring high levels of reducing power, such as liver and immune cells.

    Beta Oxidation

    • Beta oxidation is the process of breaking down fatty acids in the mitochondria, producing acetyl-CoA for energy production through the Krebs cycle; it leads to the formation of ketone bodies during fasting or uncontrolled diabetes.

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