Carbohydrate Structure and Properties
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Questions and Answers

What type of glycosidic bonds are present in amylopectin?

  • α(1→4) only
  • β(1→4) and β(1→6)
  • α(1→4) and α(1→6) (correct)
  • α(1→6) only

    • What is the main difference between amylopectin and amylose?

  • Amylopectin is composed of glucose, while amylose is composed of fructose.
  • Amylopectin is branched, while amylose is linear. (correct)
  • Amylopectin is a polysaccharide, while amylose is a monosaccharide.
  • Amylopectin is linear, while amylose is branched.

    • What is the function of the α(1→6) glycosidic bonds in amylopectin?

  • They link glucose molecules to form amylopectin.
  • They create the linear chains of amylopectin.
  • They give amylopectin its helical structure.
  • They create the branches in amylopectin. (correct)

    • Why is amylopectin considered a non-reducing sugar?

    <p>It does not contain any free aldehyde or ketone groups.</p> Signup and view all the answers

    What is the significance of the reducing end in amylopectin?

    <p>It is where new glucose units are added.</p> Signup and view all the answers

    What is the approximate percentage of α(1→6) glycosidic bonds in amylopectin?

    <p>10%</p> Signup and view all the answers

    Which of the following statements is TRUE about the structure of amylopectin?

    <p>Amylopectin is a highly branched polysaccharide with α(1→4) and α(1→6) glycosidic bonds.</p> Signup and view all the answers

    Where in nature is amylopectin found?

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

    What is the primary reason why sucrose is classified as a non-reducing sugar?

    <p>Both of its anomeric carbons are involved in a glycosidic bond.</p> Signup and view all the answers

    Which disaccharide is formed from two D-glucose residues joined by glycosidic linkage?

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

    What type of sugar is formed by the hydrolysis of sucrose?

    <p>Invert sugar</p> Signup and view all the answers

    In which disaccharide is the glycosidic bond formed between C-1 of one sugar and C-4 of another?

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

    What characteristic of the anomeric carbon affects the reducing nature of disaccharides like maltose and lactose?

    <p>It remains free for oxidation.</p> Signup and view all the answers

    What is the result of the reaction between alcohols and aldehydes or ketones in monosaccharides?

    <p>Formation of hemiacetals or hemiketals</p> Signup and view all the answers

    Which of the following statements about the cyclic structure of D-glucose is true?

    <p>D-glucose forms an intramolecular hemiacetal.</p> Signup and view all the answers

    What distinguishes α and β anomers of D-glucose?

    <p>The configuration around the anomeric carbon</p> Signup and view all the answers

    Which ring structure is formed when D-fructose undergoes cyclization?

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

    In which form do monosaccharides with five or more carbon atoms primarily exist in aqueous solution?

    <p>Both linear and cyclic forms in equilibrium</p> Signup and view all the answers

    Which type of polysaccharides is composed of two or more types of monosaccharides?

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

    What is the main function of storage polysaccharides?

    <p>Provide energy storage</p> Signup and view all the answers

    Which of the following is an example of a storage polysaccharide in plants?

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

    What distinguishes homopolysaccharides from heteropolysaccharides?

    <p>Homopolysaccharides have a single type of monosaccharide unit</p> Signup and view all the answers

    What role do structural polysaccharides play in organisms?

    <p>Structural support</p> Signup and view all the answers

    Which of the following best describes trehalose?

    <p>A non-reducing sugar in insects</p> Signup and view all the answers

    Which structural feature differentiates polysaccharides from each other?

    <p>The type of repeating monosaccharide unit</p> Signup and view all the answers

    What type of linkage joins monosaccharide units in polysaccharides?

    <p>Glycosidic linkages</p> Signup and view all the answers

    What type of sugar does not contain any chiral carbon atoms?

    <p>Dihydroxy acetone</p> Signup and view all the answers

    What determines whether a sugar is classified as a D or L isomer?

    <p>The position of the hydroxyl group on the next to last carbon</p> Signup and view all the answers

    How many stereoisomers can a monosaccharide with four chiral centers have?

    <p>16</p> Signup and view all the answers

    Which structure represents the most stable form of monosaccharides?

    <p>Cyclic structure with a six-membered ring</p> Signup and view all the answers

    What is the result of the intermolecular reaction between the carbonyl group and the hydroxyl group in monosaccharides?

    <p>Formation of a hemiacetal</p> Signup and view all the answers

    Which statement about D and L isomers is correct?

    <p>D isomers have the –OH group on the right.</p> Signup and view all the answers

    What role do chiral centers play in monosaccharides?

    <p>They create optical activity.</p> Signup and view all the answers

    How many asymmetric carbon atoms are present in glyceraldehyde?

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

    Which of the following statements about starch is NOT true?

    <p>The blue color of the starch-iodine complex is due to amylopectin.</p> Signup and view all the answers

    What is the primary structural difference between amylopectin and glycogen?

    <p>Amylopectin has α(1→6) branch points while glycogen has α(1→4) branch points.</p> Signup and view all the answers

    Why does the highly branched structure of glycogen facilitate rapid degradation?

    <p>Branching increases the number of glucose-releasing sites.</p> Signup and view all the answers

    Which of the following is NOT a reason why animals use glycogen as an energy store despite having a more abundant fat reserve?

    <p>Fat is less efficient in providing energy per unit mass than glycogen.</p> Signup and view all the answers

    What is the primary reason for storing glucose as starch or glycogen rather than in their monomeric form?

    <p>To reduce osmotic pressure within the cell.</p> Signup and view all the answers

    Which of the following statements accurately describes the process of glycogen breakdown?

    <p>Glycogen breakdown is a rapid process, with enzymes acting simultaneously on multiple branch points to release numerous glucose units.</p> Signup and view all the answers

    What is the role of enzymes in glycogen granules?

    <p>Enzymes in glycogen granules regulate both glycogen synthesis and breakdown.</p> Signup and view all the answers

    Study Notes

    Carbohydrate Structure and Properties

    • Carbohydrates are aldehyde and ketone compounds with multiple hydroxyl groups.
    • They are abundant in nature and serve various roles, including energy storage, fuels, and metabolic intermediates.
    • They are components of RNA and DNA backbones (ribose and deoxyribose).
    • Polysaccharides are constituents of bacterial and plant cell walls.
    • Carbohydrates are linked to proteins and lipids, acting as informational molecules in cell-cell interactions.
    • Carbohydrates are classified into monosaccharides, oligosaccharides, and polysaccharides.

    Monosaccharides

    • Simplest carbohydrates containing aldehyde (-CHO) or ketone (>C=O) groups and multiple hydroxyl (-OH) groups.
    • General formula: Cn(H₂O)n
    • Cannot be further hydrolyzed into simpler carbohydrates.
    • Classified by the number of carbon atoms (triose, tetrose, pentose, hexose, heptoses, etc.) and functional groups (aldoses or ketoses).
    • Examples: glucose, fructose, ribose, dihydroxyacetone.
    • Exist in linear and cyclic forms.
    • Cyclic structures form through hemiacetal formation (reaction between carbonyl and hydroxyl groups). Cyclic structures are more stable in solution.

    Monosaccharide Properties

    • Chiral centers: Most monosaccharides (except dihydroxy acetone) have chiral centers leading to stereoisomers (optical isomers).
    • D and L isomers: Sugars are designated D or L based on the configuration of the -OH group furthest from the carbonyl group. D-sugars are common in biological systems.
    • Anomers: In solution, monosaccharides with 5 or more carbons form cyclic structures and exist as anomers (α and β), based on the configuration of the hydroxyl group on the anomeric carbon.
    • Mutarotation: The process where α and β forms interconvert in solution.

    Disaccharides

    • Formed by the linkage of two monosaccharides via a glycosidic bond (an O-glycosidic linkage, specifically) between the anomeric carbon of one sugar and the hydroxyl group of another.
      • Examples: sucrose, lactose, maltose.
    • Classification: based on the type of monosaccharides and the glycosidic linkage.
    • Some disaccharides are reducing, others are not (based on if the anomeric carbon is free or involved in the linkage).

    Polysaccharides

    • Polymers composed of ten or more monosaccharide units linked by glycosidic linkages.
    • Homopolysaccharides: composed of a single type of monosaccharide unit.
      • Examples: starch, glycogen.
    • Heteropolysaccharides: composed of two or more different types of monosaccharide units.
    • Function: storage of energy, structural components (e.g., cellulose, chitin).

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    Structure and Properties of Carbohydrates PDF

    Description

    This quiz covers the essential structures and properties of carbohydrates, including their classification into monosaccharides, oligosaccharides, and polysaccharides. Explore their roles in biological systems, such as energy storage and cellular functions. Test your knowledge of key concepts like the composition of RNA and DNA backbones.

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