Carbohydrate Chemistry Quiz
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Questions and Answers

Which compound is an example of an epimer?

  • D-Erythrulose
  • D-Fructose
  • D-Glucose (correct)
  • D-Ribulose

    • What defines enantiomers in carbohydrate chemistry?

  • Compounds that are identical but differ in properties
  • Compounds that differ at multiple asymmetric carbons
  • Compounds that have the same structural formula
  • Compounds that are mirror images of each other (correct)

    • Which of the following best describes an anomer?

  • Optical isomers differing at one carbon only
  • Optical isomers representing α and β forms of sugars (correct)
  • Isomers that differ in spatial arrangement of atoms
  • Isomers that differ in the position of the carbonyl group

    • Which sugar represents an example of a mirror image form?

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

    Which statement correctly describes optical isomers?

    <p>They differ in the arrangement of hydrogen and hydroxyl groups around asymmetric carbons.</p> Signup and view all the answers

    What is the general formula for monosaccharides?

    <p>C_n (H2O)_n</p> Signup and view all the answers

    Which type of carbohydrate consists of only one sugar unit?

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

    What characterizes an asymmetric carbon atom?

    <p>It is attached to four different atoms or groups.</p> Signup and view all the answers

    What distinguishes aldoses from ketoses?

    <p>Aldoses contain an aldehyde group.</p> Signup and view all the answers

    How many carbon atoms are present in tetroses?

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

    What is the classification for carbohydrates that consist of 3 to 10 sugar units?

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

    Which of the following is a characteristic of glyceraldehyde?

    <p>It is the parent aldose.</p> Signup and view all the answers

    Which type of carbohydrate contains more than 10 sugar units?

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

    What are the two forms that aldoses and ketoses can exist in due to functional group isomerism?

    <p>Aldoses and Ketoses</p> Signup and view all the answers

    Which of the following statements about the cyclic forms of pentoses and hexoses is true?

    <p>They can form 4 or 5 carbon rings.</p> Signup and view all the answers

    In the Haworth formula, how are groups from the straight formula represented in the cyclic structure?

    <p>Left-side groups are represented upward.</p> Signup and view all the answers

    What defines the anomeric carbon in a cyclic sugar structure?

    <p>It is formed from the carbonyl carbon.</p> Signup and view all the answers

    What is the α form of sugar defined by?

    <p>The OH group is below the anomeric carbon.</p> Signup and view all the answers

    Which of the following sugars is classified as a ketose?

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

    What type of ring structure does furanose refer to?

    <p>4 carbon ring</p> Signup and view all the answers

    What is a common characteristic of aldose and ketose isomers?

    <p>They have the same molecular formula.</p> Signup and view all the answers

    What type of polysaccharides contain only one type of monosaccharide?

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

    Which of the following is a storage form of carbohydrates in plants?

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

    What type of linkage connects the D-Glucose units in cellulose?

    <p>β1-4 glucosidic linkage</p> Signup and view all the answers

    Which polysaccharide comprises about 10% of the wet weight of the liver?

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

    Which form of starch is linear and represents about 15% of starch granules?

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

    What is the primary function of inulin in medical testing?

    <p>Assessing renal function</p> Signup and view all the answers

    How are starch granules primarily hydrolyzed to produce glucose?

    <p>By α-amylase</p> Signup and view all the answers

    Which of the following characteristics is true for cellulose?

    <p>It is a linear polymer</p> Signup and view all the answers

    What type of linkage does cellulose contain that prevents its hydrolysis by amylase?

    <p>β1-4 glucosidic linkage</p> Signup and view all the answers

    What is the primary dietary function of cellulose in preventing constipation?

    <p>Adding bulk to food</p> Signup and view all the answers

    Which of the following is not classified as a glycosaminoglycan (GAG)?

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

    Which statement about proteoglycans is correct?

    <p>They consist of GAGs linked to a protein core.</p> Signup and view all the answers

    What is a major role of glycosaminoglycans (GAGs) in the extracellular matrix?

    <p>Attracting cations and forming hydrogels</p> Signup and view all the answers

    Which of the following is a sulfate-containing glycosaminoglycan?

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

    What percentage of proteoglycans is typically composed of carbohydrates?

    <p>95%</p> Signup and view all the answers

    What function do glycosaminoglycans serve in synovial fluid?

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

    Study Notes

    Carbohydrate Chemistry

    • Carbohydrates are polyhydroxy alcohols with functional aldehyde or ketol groups.
    • The ratio between Carbon and H2O in carbohydrates is usually 1:1.
    • Carbohydrates are classified based on the products formed during hydrolysis.

    Monosaccharides

    • General Formula: Cn(H2O)n
    • Classification:
      • Number of Carbon Atoms:
        • Trioses (3 carbons): Aldotrioses and Ketotrioses
        • Tetroses (4 carbons): Aldotetroses and Ketotetoses
        • Pentoses (5 carbons): Aldopentoses and Ketopentoses
        • Hexoses (6 carbons): Aldohexoses and Ketohexoses
        • Heptoses (7 carbons): Ketoheptoses
      • Functional Group:
        • Aldoses: Contain an aldehyde group.
        • Ketoses: Contain a ketone group.

    Aldoses

    • Parent Aldose: Glyceraldehyde.
    • Glyceraldehyde Structure:
      • 1st Carbon: Aldehyde group (H-C=O)
      • 2nd Carbon: Secondary alcohol group (H-C-OH)
      • 3rd Carbon: Primary alcohol group (CH2OH)
    • D and L Forms: Glyceraldehyde exists in D or L forms.
    • Higher Aldoses: Formed by inserting a secondary alcohol group below the aldehyde group.

    Asymmetric Carbon Atoms

    • A carbon atom attached to four different atoms or groups.

    Isomers

    • Optical Isomers: Compounds with the same molecular formula but different orientations of H or OH around one or more asymmetric carbons.
      • Epimers: Optical isomers with more than one asymmetric carbon, where all are the same except for one.
        • Glucose and Mannose: Epimers at C2.
        • Glucose and Galactose: Epimers at C4.
      • Anomers: Optical isomers representing the α and β forms of a sugar in its ring structure.
        • α, D-glucopyranose and β, D-glucopyranose.
      • Enantiomers: The D and L forms of a sugar; they are mirror images.
        • D-glyceraldehyde and L-glyceraldehyde.
        • D-glucose and L-glucose.
    • Aldose-Ketose Isomers: Isomers with the same molecular formula but different functional groups.
      • Example:
        • Trioses: Glyceraldehyde (aldose) and Dihydroxyacetone (ketose)
        • Tetroses: Erythrose (aldose) and Erythrulose (ketose)
        • Pentoses: Ribose and Xylose (aldoses) and Ribulose and Xylulose (ketoses)
        • Hexoses: Glucose, Galactose, and Mannose (aldoses) and Fructose (ketose)

    Ring Structure of Monosaccharides

    • Pentoses and Hexoses can exist in cyclic forms.
    • The cyclic form is due to a reaction between the carbonyl group (C=O) of the aldehyde or ketone with an alcoholic hydroxyl group.
      • Furanose: 4-carbon ring.
      • Pyranose: 5-carbon ring.
    • Haworth Formula: Describes the cyclic structure.
      • Groups on the left side in the straight formula are written upwards.
      • Groups on the right side in the straight formula are written downwards.
    • Anomeric Carbon:
      • The first carbon in the cyclic structure becomes an asymmetric carbon.
      • α Form: OH group is on the right side of the anomeric carbon.
      • β Form: OH group is on the left side of the anomeric carbon.

    Polysaccharides

    • Polymers of monosaccharides.
    • Classified based on the type of monosaccharide units present.

    Homopolysaccharides

    • Contain only one type of monosaccharide.
    • Examples:
      • Glucans: Formed of D-glucose units.
        • Starch
        • Glycogen
        • Cellulose
      • Fructans:
        • Inulin: Formed of D-fructose units, found in plants, used to assess renal functions.

    Glucans

    • Starch:
      • Storage form of carbohydrate in plants.
      • Sources: Cereals, legumes, and tubers.
      • Types:
        • Amylose (15%):
          • Linear polymer of glucose units linked by α1-4 glycosidic bonds.
          • Found in the inner part of starch granules.
          • Hydrolyzed by α-amylase to maltose, then to D-glucose.
        • Amylopectin (85%):
          • Branched polymer of glucose units with α1-4 glycosidic bonds and α1-6 glycosidic bonds at branching points.
          • Found in the outer part of starch granules.
          • Hydrolyzed by α-amylase to maltose and isomaltose, then to D-glucose.
    • Glycogen (Animal Starch):
      • Storage form of carbohydrate in animals.
      • Found in the liver and muscles.
      • More branched than amylopectin and has a higher molecular weight.
      • Hydrolyzed by α-amylase to maltose and isomaltose, then to D-glucose.
    • Cellulose:
      • Linear polymer of β, D-glucose units linked by β1-4 glycosidic bonds.
      • Found in plants, vegetables, and cotton.
      • Insoluble in water.
      • Not digested by humans because the β1-4 glycosidic linkage is not cleaved by amylase.
      • Important for dietary fiber and preventing constipation.

    Heteropolysaccharides

    • Contain more than one type of monosaccharide.
    • Examples:
      • Glycosaminoglycans (GAGs) or Mucopolysaccharides
      • Proteoglycans

    Glycosaminoglycans (GAGs)

    • Long, unbranched heteropolysaccharides.
    • Composed of uronic acid and amino sugar units.
    • Classification:
      • Sulfate Free GAGs:
        • Hyaluronic acid
      • Sulfate Containing GAGs:
        • Chondroitin sulfate
        • Dermatan sulfate
        • Keratan sulfate
        • Heparin
        • Heparan sulfate

    Proteoglycans

    • GAGs covalently linked to a protein core.
    • Structure: 95% carbohydrates and 5% proteins.
    • Site: Extracellular matrix, ground substance in association with extracellular proteins.
    • Functions of GAGs and Proteoglycans:
      • Components of the extracellular matrix.
      • Attract water, forming hydrated gels.
      • Act as lubricants in synovial fluid.
      • Play roles in cell signaling and immune responses.

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