Carbohydrates and Their Types
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Questions and Answers

What are the simplest form of carbohydrates called?

  • Polysaccharides
  • Oligosaccharides
  • Disaccharides
  • Monosaccharides (correct)
  • D-glucose and L-glucose are known as epimers.

    False

    What type of carbohydrate consists of 2-10 monosaccharides linked together?

    Oligosaccharides

    The general formula for monosaccharides is Cn(H2O)n, where 'n' represents the number of __________.

    <p>carbon atoms</p> Signup and view all the answers

    Match the following types of carbohydrates with their definitions:

    <p>Monosaccharides = Simple sugars that cannot be broken down further Oligosaccharides = Carbohydrates consisting of 2-10 monosaccharides Polysaccharides = Large molecules made of many monosaccharide units Disaccharides = A specific type of oligosaccharide made of two monosaccharides</p> Signup and view all the answers

    Which of the following is an example of a polysaccharide?

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

    Alpha-anomers and beta-anomers form due to the cyclization of pentoses and hexoses.

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

    What is created during the cyclization of an aldose like glucose?

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

    Which of the following statements about the stability of alpha-D-glucose and beta-D-glucose is true?

    <p>Beta-D-glucose is more stable due to its equatorial hydroxyl group.</p> Signup and view all the answers

    Beta-D-glucose has its hydroxyl group in the axial position.

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

    What is the product of the oxidation of alpha-D-glucose in the presence of silver in Tollen’s Test?

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

    The process of converting monosaccharides into deoxy sugars involves substituting a hydrogen atom for one of the ______ groups.

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

    Match the following oxidation reactions with their corresponding tests:

    <p>Tollen's Test = Oxidizes aldehyde groups to carboxylic acids Benedict's Test = Tests for reducing sugars Fehling's Test = Identifies aldehydes by producing a colored precipitate Barfoed's Test = Differentiates between monosaccharides and disaccharides</p> Signup and view all the answers

    Which of the following is a common alditol used as a sweetener?

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

    Sugar phosphates are a type of sugar ester formed from the reaction of alcohol with phosphoric acid.

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

    What defines a full acetal in carbohydrate chemistry?

    <p>Both -OH groups of a hemiacetal are replaced by -OR groups.</p> Signup and view all the answers

    Study Notes

    Carbohydrates

    • Carbohydrates are organic compounds composed of carbon, hydrogen, and oxygen.
    • They are categorized into monosaccharides, oligosaccharides, and polysaccharides.

    Monosaccharides

    • Simplest form of carbohydrates, also called simple sugars.
    • General formula: Cn(H₂O)n
    • Examples: glucose, fructose, galactose
    • Building blocks of carbohydrates
    • Cannot be broken down further by hydrolysis.

    Oligosaccharides

    • Formed by linking a few (2-10) monosaccharides.
    • Examples: disaccharides like sucrose (table sugar) and lactose (milk sugar).

    Polysaccharides

    • Large molecules composed of many monosaccharide units.
    • Examples: starch, cellulose, glycogen.

    Stereoisomers

    • Enantiomers: Mirror-image stereoisomers
      • D-glucose and L-glucose are enantiomers.
    • Epimers: Sugars that differ in configuration at only one chiral center.
      • D-glucose and D-mannose are C-2 epimers.
      • D-glucose and D-galactose are C-4 epimers.

    Cyclization and Anomers

    • Monosaccharides with 5 or 6 carbon atoms often form ring structures.
    • Cyclization occurs when a carbonyl group reacts with a hydroxyl group on the same molecule.
    • This creates a new chiral center (anomeric carbon).
    • The resulting ring structure exists in two forms: α-anomer and β-anomer.
    • Hemiacetals and hemiketals are more stable than their corresponding open-chain forms.

    Haworth Projections

    • Two-dimensional representations of the cyclic forms of monosaccharides.

    Mutarotation

    • Interconversion of α and β anomers.

    Chair Conformation of Glucose

    • β-D-glucose is more stable than α-D-glucose.
    • The equatorial position of the hydroxyl group on C1 in β-forms is more stable than the axial position in α.

    Oxidation Reactions

    • Oxidation reactions convert aldoses to lactones.
    • Tollens' test example of an oxidation reaction.
    • A cyclic ester linking the carboxyl group and a sugar alcohol is called a lactone.

    Reduction Reactions

    • Reduction reactions convert sugars to deoxy sugars or alditols.
    • Deoxy sugars: a hydrogen atom replaces a hydroxyl group, examples include L-fucose and D-2-deoxyribose.
    • Alditols: carbonyl group reduced to a hydroxyl group, examples include xylitol and sorbitol.

    Sugar Esters, Phosphates, and Glycosides

    • Sugar esters result from reacting alcohol with an acid.
    • Sugar phosphates are sugar esters.
    • Glycosides are formed when hemiacetals or hemiketals react with another alcohol
    • Full acetals/ketals: complete replacement of both -OH groups with -OR groups.

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    Description

    Explore the fascinating world of carbohydrates, including their classifications into monosaccharides, oligosaccharides, and polysaccharides. This quiz will test your understanding of their structures, examples, and functions, including important concepts like stereoisomers.

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