Organic Chemistry II: Carbohydrate Structure & Functions
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Questions and Answers

What is the main characteristic that defines carbohydrates?

  • Presence of amine groups
  • Presence of multiple hydroxyl groups (correct)
  • Presence of carboxyl groups
  • Presence of methyl groups
  • What is the purpose of the Fischer projection in carbohydrate representation?

  • To show the molecular formula of carbohydrates
  • To show the branching of carbohydrates
  • To show the ring structure of carbohydrates
  • To show the absolute configuration of monosaccharides (correct)
  • What is the term for the process by which a monosaccharide changes from an α-anomer to a β-anomer?

  • Cyclization
  • Hemiacetal formation
  • Mutarotation (correct)
  • Epimerization
  • What type of bond is formed during the cyclization of carbohydrates?

    <p>Hemiacetal bond</p> Signup and view all the answers

    What is the term for a pair of non-superimposable mirror images of a monosaccharide?

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

    What is the term for a monosaccharide with a chain length of 3-7 carbon atoms?

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

    What is the primary function of carbohydrates as a source of energy?

    <p>When oxidized</p> Signup and view all the answers

    What is the classification of sucrose, lactose, and maltose?

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

    What is the role of carbohydrates in the structural materials of cells?

    <p>Constitute the cell walls of bacteria and plants</p> Signup and view all the answers

    What is the result of hydrolyzing oligosaccharides?

    <p>More than 2 but less than 10 monosaccharides</p> Signup and view all the answers

    What is the function of carbohydrates in glycoproteins and glycolipids?

    <p>Act as markers for cellular recognition</p> Signup and view all the answers

    What is the classification of glucose, mannose, galactose, fructose, and ribose?

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

    Study Notes

    Carbohydrate Structure and Functions

    Definition and Representation

    • Carbohydrates are aldehyde or ketone compounds with multiple hydroxyl groups.
    • They can be represented by chemical formulae, Fischer projection, and Haworth projection.

    Roles of Carbohydrates in Nature

    • Fuel source: important source of energy when oxidized
    • Energy storage: starch in plants; glycogen in liver and muscle of animals
    • Structural materials: DNA and RNA, cell walls of bacteria and plants; chitin in exoskeleton
    • Intermediates of metabolism
    • Recognition: glycoproteins and glycolipids act as markers for cellular recognition, blood group determination, cell adhesion, cell migration, immune response, and blood clotting

    Classification of Carbohydrates

    Monosaccharides

    • Cannot be hydrolyzed into simpler sugars
    • Examples: glucose, mannose, galactose, fructose, and ribose

    Disaccharides

    • Hydrolysis yields 2 monosaccharides (sugars)
    • Examples: sucrose, lactose, maltose, cellubiose, and gentiobiose

    Oligosaccharides (Few Sugars)

    • Hydrolysis produces >2 but (<10) monosaccharides

    Important Carbohydrates

    Composition and Bonding

    • Lactose: composed of glucose and galactose; α-1,4-glycosidic bond
    • Maltose: composed of two glucose molecules; α-1,4-glycosidic bond
    • Sucrose: composed of glucose and fructose; α-1,2-glycosidic bond
    • Starch, glycogen, cellulose, and chitin: composed of multiple glucose molecules; α-1,4-glycosidic bonds

    Stereochemistry

    • Enantiomers: non-superimposable mirror images
    • Diastereoisomers: stereoisomers that are not enantiomers
    • Anomers: stereoisomers that differ in configuration at the anomeric carbon
    • Epimers: stereoisomers that differ in configuration at a single carbon atom
    • D and L stereoisomers of glyceraldehyde
    • Fischer projection and Haworth projection of D-glucose

    Cyclization and Anomers

    • Cyclization arises through the formation of hemiacetal and hemiketal bonds
    • Mutarotation: change in anomeric configuration over time
    • α- and β-anomers of monosaccharides

    Reducing and Non-Reducing Sugars

    • Sugars with a free aldehyde or ketone group are reducing sugars
    • Examples of reducing sugars: glucose, fructose, and lactose
    • Examples of non-reducing sugars: sucrose

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    Description

    This quiz covers the structure and functions of carbohydrates, including their representation by chemical formulae, Fischer and Haworth projections, and their roles in nature. Learn about the classification of carbohydrates into mono-, di-, oligo- and polysaccharides.

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