Monosaccharides: Structure and Isomers
40 Questions
1 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the layered structure of bacterial cell walls built from?

  • Alternating units of cellulose and chitin
  • Alternating units of protein and lipids
  • Alternating units of GlcNAc and N-acetylmuramic acid (correct)
  • Alternating units of starch and glycogen

    • What is the result of the elimination of water between the anomeric hydroxyl of a cyclic monosaccharide and the hydroxyl group of another compound?

  • Formation of a peptide bond
  • Formation of an ether bond
  • Formation of an amide bond
  • Formation of an O-glycoside (correct)

    • Which of the following glycosides is a cardiac glycoside and Na+/K+ ATPase inhibitor?

  • Ouabain (correct)
  • Sucrose
  • Maltose
  • Amygdalin

    • What is the stereoconfiguration of the sugar monomers involved in the formation of maltose?

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

    What is the common feature of all disaccharides involving the anomeric hydroxyl of at least one sugar?

    <p>Participation in a glycosidic bond</p> Signup and view all the answers

    What is the type of linkage involved in the formation of sucrose?

    <p>1à 2</p> Signup and view all the answers

    Which of the following disaccharides involves the anomeric hydroxyl of both sugars?

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

    What is the importance of the order of the two monomer units in disaccharides?

    <p>It determines the type of glycosidic bond formed</p> Signup and view all the answers

    What is the key difference between conformational isomers and configurational isomers?

    <p>The ability to interconvert without breaking and re-forming bonds</p> Signup and view all the answers

    What is the role of sugar phosphates in metabolism?

    <p>To function as activated compounds in syntheses</p> Signup and view all the answers

    What is the product of mild oxidation of an aldose with alkaline Cu(II) (Fehling's solution)?

    <p>Aldonic acids</p> Signup and view all the answers

    What is the result of enzyme-catalyzed oxidation of monosaccharides?

    <p>Formation of uronic acids</p> Signup and view all the answers

    What is the significance of uronic acids in natural polysaccharides?

    <p>They are important constituents of certain natural polysaccharides</p> Signup and view all the answers

    What is the equilibrium state of free aldonic acids in solution?

    <p>In equilibrium with lactones</p> Signup and view all the answers

    What is the class of compounds formed by the reduction of the carbonyl group on a sugar?

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

    Which of the following is an important naturally occurring alditol?

    <p>All of the above</p> Signup and view all the answers

    What is the primary reason why lactose is considered a reducing sugar?

    <p>The presence of a potential free aldehyde group in the glucose residue</p> Signup and view all the answers

    What determines the shape of an oligosaccharide molecule?

    <p>The configuration of the anomeric hydroxyl group of each residue</p> Signup and view all the answers

    Why do different enzymes catalyze the hydrolysis of maltose and cellobiose?

    <p>Because they have different anomeric hydroxyl group configurations</p> Signup and view all the answers

    What is the purpose of the 'bent bonds' in drawing glycosidic bonds?

    <p>To allow the Haworth projections of the monomers to be drawn in parallel</p> Signup and view all the answers

    What is the correct sequence for writing the structure of a disaccharide?

    <p>Starting with the non-reducing end at the left</p> Signup and view all the answers

    What is the term for the end of an oligosaccharide that has a potential free aldehyde group?

    <p>Reducing end</p> Signup and view all the answers

    Why is sucrose considered a non-reducing sugar?

    <p>Because neither residue has a potential free aldehyde group</p> Signup and view all the answers

    What is the prefix used to designate the anomeric form of a monosaccharide?

    <p>a- or b-</p> Signup and view all the answers

    Where is hyaluronic acid synthesized in the body?

    <p>Plasma membrane</p> Signup and view all the answers

    What is the function of heparin in the body?

    <p>To inhibit blood clotting</p> Signup and view all the answers

    What is the characteristic of the cell wall of a Gram-positive bacterium?

    <p>Thick peptidoglycan layer</p> Signup and view all the answers

    What is the cross-linking component in the cell wall of a Gram-positive bacterium?

    <p>Glycine pentapeptides</p> Signup and view all the answers

    What is the function of hyaluronan in the extracellular matrix?

    <p>To facilitate cell migration and proliferation</p> Signup and view all the answers

    What is the characteristic of the cell wall of a Gram-negative bacterium?

    <p>Thin peptidoglycan layer</p> Signup and view all the answers

    What is the cross-linking component in the cell wall of a Gram-negative bacterium?

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

    What is the structure of lipoteichoic acid?

    <p>D-Alanyl and NAG groups arranged irregularly on the chain</p> Signup and view all the answers

    What is the primary function of transpeptidase enzyme in peptidoglycan synthesis?

    <p>To form cross-links between adjacent peptidoglycan chains</p> Signup and view all the answers

    What is the mechanism of penicillin's action on the transpeptidase enzyme?

    <p>Penicillin binds to the active site of the enzyme, forming an inactive complex</p> Signup and view all the answers

    What is the result of penicillin's inhibition of transpeptidase enzyme on the bacterial cell?

    <p>The cell wall becomes weaker and more susceptible to lysis</p> Signup and view all the answers

    What is the specific component of penicillin that binds to proteins?

    <p>The β-lactam ring</p> Signup and view all the answers

    What is the effect of penicillin on the synthesis of peptidoglycans?

    <p>It inhibits the completion of peptidoglycan synthesis</p> Signup and view all the answers

    What is the consequence of the weakened cell wall due to penicillin's action?

    <p>Water flows uncontrollably into the cell, leading to lysis</p> Signup and view all the answers

    What is the specific mechanism by which penicillin leads to cell lysis?

    <p>Penicillin disrupts the cell's osmotic gradient</p> Signup and view all the answers

    What is the primary target of penicillin's action?

    <p>The transpeptidase enzyme</p> Signup and view all the answers

    Study Notes

    Monosaccharides

    • Conformational isomers are distinguished from configurational isomers in that the former can interconvert without breaking and re-forming bonds.
    • Epimers are stereoisomers differing in their configuration about only one asymmetric carbon atom.

    Derivatives of Monosaccharides

    • Sugar phosphates are important intermediates in metabolism, functioning as activated compounds in syntheses.
    • Oxidation of monosaccharides can proceed in several ways, depending upon the oxidizing agent used, producing aldonic acids.
    • Enzyme-catalyzed oxidation of monosaccharides gives other products, including uronic acids such as glucuronic acid.
    • Uronic acids are important constituents of certain natural polysaccharides.
    • Free aldonic acids, such as gluconic acid, are in equilibrium in solution with lactones, which are cyclic esters.
    • Reduction of the carbonyl group on a sugar gives rise to the class of polyhydroxy compounds called alditols.
    • Important naturally occurring alditols include erythritol, D-mannitol, and D-glucitol (also known as sorbitol).
    • D-glucitol is part of bacterial cell wall, which is built from alternating units of GlcNAc and N-acetylmuramic acid, forming a layered structure called peptidoglycan.

    Oligosaccharides

    • Elimination of water between the anomeric hydroxyl of a cyclic monosaccharide and the hydroxyl group of another compound yields an O-glycoside.
    • The acetal bond formed is referred to as a glycosidic bond.
    • Two naturally occurring glycosides are Ouabain (cardiac glycoside, Na+/K+ ATPase inhibitor) and amygdalin (cyanide!), which are highly toxic glycosides produced by plants.
    • Distinguishing features of different disaccharides include:
      • The two specific sugar monomers involved, and their stereoconfigurations.
      • The carbons involved in the linkage.
      • The order of the two monomer units, if they are different kinds.
      • The configuration of the anomeric hydroxyl group of each residue.
    • Note the convention used to draw glycosidic bonds, where the “bent bonds” allow the Haworth projections of the monomers to be drawn in parallel.

    Polysaccharides

    • Hyaluronic acid is distributed widely throughout connective, epithelial, and neural tissues, and is unique among glycosaminoglycans in that it is nonsulfated, forms in the plasma membrane instead of the Golgi apparatus, and can be very large.
    • Hyaluronic acid is one of the chief components of the extracellular matrix, and contributes significantly to cell proliferation and migration.
    • Heparin is a highly sulfated glycosaminoglycan, appears to be a natural anticoagulant, and is found in many body tissues.
    • Heparin binds strongly to a blood protein, antiprothrombin III, and the complex inhibits enzymes of the blood clotting process.
    • The cell wall of a Gram-positive bacterium, S. aureus, consists of a thick peptidoglycan layer made up of polysaccharide chains and short peptides.
    • The cell wall of a Gram-negative bacterium, E. coli, has a thin peptidoglycan layer and an outer lipid membrane.

    Glycoconjugates of Interest

    • The structure of a lipotechoic acid consists of D-Alanyl and NAG groups arranged irregularly on the chain, which is anchored in the membrane by lipid.
    • The cross-linking reaction in peptidoglycan synthesis involves the action of a transpeptidase enzyme, which is inhibited by penicillin.
    • Penicillin inhibits the completion of the synthesis of peptidoglycans by binding to proteins with the β-lactam ring, causing the cell wall to weaken due to fewer cross-links, and ultimately leading to cell lysis.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Lecture 4: Carbohydrates PDF

    Description

    This quiz covers the structure of sugar molecules, including conformational isomers, configurational isomers, and epimers.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser