Biochemistry of Carbohydrates I, II
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Questions and Answers

What is the primary biological significance of carbohydrates in human nutrition?

  • Main component of hormones
  • Important for fat storage
  • Major source of energy (correct)
  • Source of protein

    • Which type of carbohydrate consists of 2-10 monosaccharide units?

  • Polysaccharides
  • Monosaccharides
  • Disaccharides only
  • Oligosaccharides (correct)

    • Which of the following is NOT a classification of monosaccharides based on the number of carbon atoms?

  • Hexodes (correct)
  • Trioses
  • Tetroses
  • Pentoses

    • Which monosaccharide serves as a structural component in nucleic acids?

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

    What is the significance of glucose in the body?

    <p>It is the primary energy source.</p> Signup and view all the answers

    How are fructose and glucose related in terms of sweetness?

    <p>Fructose is sweeter than glucose.</p> Signup and view all the answers

    Which statement about polysaccharides is accurate?

    <p>They consist of more than 10 monosaccharide units.</p> Signup and view all the answers

    Which carbohydrate is a subunit of the milk sugar lactose?

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

    What is the role of Mannitol in medical treatment?

    <p>To reduce intracranial hypertension</p> Signup and view all the answers

    Which of the following disaccharides is classified as a reducing sugar?

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

    What type of linkage is present in Maltose?

    <p>α-1,4-glucosidic linkage</p> Signup and view all the answers

    What effect does phytic acid have on mineral absorption?

    <p>Inhibits absorption of calcium, magnesium, and iron</p> Signup and view all the answers

    Which sugar is identified as the most suitable for baby feeding?

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

    What is a major characteristic of Sucrose?

    <p>It does not have a free aldehyde group</p> Signup and view all the answers

    Which of these is NOT a property of lactose?

    <p>It causes colic in infants</p> Signup and view all the answers

    What is the composition of Inositol?

    <p>A sugar alcohol with 6 OH groups</p> Signup and view all the answers

    What role does hyaluronic acid play in the body?

    <p>Acts as a lubricant in joint synovial fluids</p> Signup and view all the answers

    Which of the following is true about the enzyme hyaluronidase?

    <p>It hydrolyzes hyaluronic acid</p> Signup and view all the answers

    Chondroitin sulfate is primarily found in which of the following structures?

    <p>Cornea of the eye</p> Signup and view all the answers

    What is a primary function of heparin in the body?

    <p>Prevents intravascular clotting</p> Signup and view all the answers

    Which property of sulfated mucopolysaccharides contributes to their function in tissues?

    <p>Ionizable OH and sulfate groups creating negative charges</p> Signup and view all the answers

    What type of linkage connects the anomeric carbons in sucrose?

    <p>α-β-1,2 linkage</p> Signup and view all the answers

    Which of the following is a characteristic of cellulose?

    <p>Indigestible in humans due to β-glycosidic linkages</p> Signup and view all the answers

    Which polysaccharide serves as a stored form of carbohydrates in animals?

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

    Which of the following is a major source of starch?

    <p>Cereals and tubers</p> Signup and view all the answers

    What is the structural form of carbohydrates in plant cells?

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

    How is amylose characterized in terms of its molecular structure?

    <p>Helical straight chain</p> Signup and view all the answers

    What role does dietary fiber, such as cellulose, play in human health?

    <p>Increases the bulk of stools</p> Signup and view all the answers

    Which enzyme is crucial for the digestion of glycogen?

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

    What is one of the functions of fermentation by intestinal bacteria on dietary components?

    <p>It produces volatile fatty acids that can be anticancer for colon cells.</p> Signup and view all the answers

    How does dietary fiber help in managing blood glucose levels?

    <p>By slowing down gastric emptying time.</p> Signup and view all the answers

    What biochemical role does dextran play in medical treatments?

    <p>It serves as a plasma substitute in cases of shock.</p> Signup and view all the answers

    Which statement best describes neutral nitrogenous heteropolysaccharides?

    <p>They do not contain uronic acids or sulfate groups.</p> Signup and view all the answers

    What characterizes hyaluronic acid as a unique glycosaminoglycan (GAG)?

    <p>It is un-sulfated and not attached to proteins.</p> Signup and view all the answers

    Which substance is a treatment for iron deficiency anemia when combined with dextran?

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

    Which of the following statements is true regarding acidic nitrogenous heteropolysaccharides?

    <p>They contain uronic acids and may include sulfate groups.</p> Signup and view all the answers

    What is not a function of dietary fiber regarding toxins and cholesterol?

    <p>It increases the absorption of dietary cholesterol.</p> Signup and view all the answers

    Which sugar is the main sugar found in bee's honey and is better for diabetic patients than glucose?

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

    Which of the following is classified as an amino sugar?

    <p>Sialic acid</p> Signup and view all the answers

    What type of sugar is Glucuronic acid and what is one of its roles?

    <p>Sugar acid; aids in drug detoxication</p> Signup and view all the answers

    Which sugar alcohol is formed from the reduction of glucose and is used in medical industries?

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

    Which amino sugar is found in the structure of some mucopolysaccharides?

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

    L-Fucose and L-Rhamnose are both deoxysugars. What is their significance?

    <p>They are essential for the structure of glycoproteins in blood group substances.</p> Signup and view all the answers

    What is the main role of L-ascorbic acid synthesized from glucose?

    <p>Serving as an antioxidant</p> Signup and view all the answers

    Which sugar is specifically formed by the reduction of glyceraldehyde?

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

    Study Notes

    Biochemistry of Dietary, Functional and Structural Carbohydrates I, II

    • Carbohydrates are aldehyde or ketone derivatives of polyhydric alcohols
    • Carbohydrates are the chief source of energy, forming 60% of the human diet
    • They are important structural components in human cells and nucleic acids
    • Carbohydrates are involved in the synthesis of antigens, such as blood group substances
    • Carbohydrates are part of hormones, their receptors, and immunoglobulins
    • Hyaluronic acid, a polysaccharide, is crucial for joint lubrication

    Objectives

    • Identify different classes of carbohydrates and their biological importance
    • Define the chemistry and functions of monosaccharides, oligosaccharides, and their derivatives
    • Define and classify polysaccharides
    • Discuss the structure and function of medically important homo- and hetero-polysaccharides

    Definition of Carbohydrates

    • Carbohydrates are aldehyde (CHO) or ketone (C=O) derivatives of polyhydric alcohols or compounds that yield these derivatives on hydrolysis.

    Classification of Carbohydrates

    • Monosaccharides: Simple sugars containing one sugar unit. These are the simplest form of sugars.
    • Oligosaccharides: Contain 2-10 monosaccharide units per molecule.
    • Polysaccharides: Contain more than 10 monosaccharide units per molecule.

    I. Monosaccharides

    • Classified according to the number of carbon atoms:
      • Trioses (3 carbons)
      • Tetroses (4 carbons)
      • Pentoses (5 carbons)
      • Hexoses (6 carbons)
    • Each group further subdivided by functional chemical groups:
      • Aldoses (aldehyde group)
      • Ketoses (ketone group)

    Medical Significance of Some Monosaccharides

    • Ribose: Structural component in nucleic acids and free nucleotides
    • Glucose: Grape sugar, blood sugar, or dextrose; other hexoses need to be converted to glucose for use in the body. Appears in urine in diabetes mellitus
    • Mannose: Subunit in glycoproteins and sialic acid, part of gangliosides
    • Galactose: Subunit of lactose (milk sugar), part of glycolipids and glycoproteins
    • Fructose: Sweetest sugar; main sugar in honey; its metabolism isn't affected in diabetic patients

    Sugar Derivatives of Monosaccharides with Medical Importance

    • Amino sugars (sugaramines): Replace the hydroxyl group at C2 with an amino group
      • Glucosamine (Chitosamine): Part of some mucopolysaccharides
      • Galactosamine (Chondrosamine): Part of sulfate-containing mucopolysaccharides
      • Mannosamine: Part of antibiotics (e.g., erythromycin)
      • Sialic acid: Part of glycolipids and glycoproteins
    • Deoxysugars: Replace a hydroxyl group with a hydrogen atom.
      • Deoxyribose: Part of DNA structure
      • L-Fucose, L-Rhamnose: Part of glycoproteins in blood group substances
    • Sugar acids: Products of sugar oxidation.
      • Gluconic acid: Used as calcium gluconate for intravenous calcium supplementation
      • L-ascorbic acid (vitamin C): Synthesized in plants and some animals; an antioxidant
      • Sialic acid
      • Glucuronic acid: Synthesized in the liver; part of mucopolysaccharides (e.g., hyaluronic acid); involved in drug detoxification
    • Sugar alcohols: Products of sugar reduction.
      • Glyceraldehyde reduction gives glycerol: Part of lipids
      • Ribose reduction gives ribitol: Part of vitamin B2
      • Glucose reduction gives sorbitol: Used in medical industries; accumulates in cells in diabetes, causing osmotic damage
      • Mannose reduction gives mannitol: Used intravenously to reduce intracranial hypertension
    • Inositol: A sugar alcohol with six hydroxyl groups; found in high concentrations in bran and combines with phosphoric acid to form phytic acid ; part of vitamin B complex.

    II. Oligosaccharides

    • A. Disaccharides:
      • 1. Reducing Disaccharides: Have a free aldehyde group
        • Maltose: Two α-glucose units linked by α-1,4-glucosidic linkage
        • Lactose: β-galactose and α-glucose linked by β-1,4-glucosidic linkage
      • 2. Non-reducing Disaccharides: Have no free aldehyde group
        • Sucrose: α-glucose and β-fructose linked by α-β-1,2-linkage

    III. Polysaccharides

    • Definition: Contain more than 10 monosaccharide units per molecule.
    • Classification:
      • 1. Homopolysaccharides: Produce only one type of monosaccharide on hydrolysis:
        • Glucosans: Starch, dextrins, glycogen, cellulose
        • Fructosans: Inulin
        • Galactosans: Agar agar
        • N-acetyl-glucans: Chitin
      • 2. Heteropolysaccharides: Produce several types of sugars on hydrolysis;
        • A. Neutral nitrogenous (Glycoproteins): Does not contain uronic acids
        • B. Acidic nitrogenous (Mucopolysaccharides, Glycosaminoglycans & Proteoglycans): Contain uronic acids
          • Sulfur-free: Hyaluronic acid
          • Sulfur-containing: Chondroitin sulfate, Heparin

    Additional information:

    • Cellulose: Indigestible in humans due to lack of enzymes to hydrolyze β-glycosidic linkages; crucial for dietary fiber
    • Dextran: Synthesized by bacteria; used as a blood substitute for shock.
    • Hyaluronic Acid: A sulfur-free mucopolysaccharide; crucial for joint lubrication, preventing bacterial invasion of the skin, maintaining tissue structure.
    • Hyaluronidase: An enzyme that hydrolyzes hyaluronic acid; present in sperm, bacteria, snake/scorpion venom; used medicinally to dissolve mucus.
    • Chondroitin Sulfate: A sulfated mucopolysaccharide; present in connective tissues (cornea, tendons, ligaments, cartilage) providing structure and water absorption capacity.
    • Heparin: Anticoagulant produced by mast cells; prevents intravascular clotting and used in cases of increased coagulability.

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    Biochemistry of Dietary, Functional, and Structural Carbohydrates I, II PDF

    Description

    Explore the intricate world of carbohydrates in this quiz that covers their chemical structure, biological functions, and importance in human health. From monosaccharides to polysaccharides, test your understanding of how these fundamental macromolecules contribute to energy production, structural integrity, and various biological processes.

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