Biochem 7.2 Untitled Quiz
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Questions and Answers

What is the term used for the chemical linkage between two monosaccharides?

  • Peptide bond
  • Glycosidic bond (correct)
  • Fructose bond
  • Ether bond

    • What is released during the formation of a glycosidic bond?

  • Glucose
  • Water (correct)
  • Oxygen
  • Carbon dioxide

    • What term describes carbohydrates formed from several monosaccharides linked together?

  • Saccharides
  • Peptides
  • Glycans (correct)
  • Nucleotides

    • Which of the following may NOT form a glycosidic bond with monosaccharides?

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

    What happens to monosaccharides upon glycosidic bond formation?

    <p>They become monosaccharide residues</p> Signup and view all the answers

    Which best describes the term 'oligosaccharides'?

    <p>A few sugars</p> Signup and view all the answers

    What type of reaction occurs when a glycosidic bond forms?

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

    Which of the following statements about glycosidic bonds is correct?

    <p>They may link carbohydrates to proteins or lipids.</p> Signup and view all the answers

    What is the primary function of polysaccharides in cells?

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

    Which type of glycosidic bond is found in the simplest form of starch, amylose?

    <p>α-1,4-glycosidic bonds</p> Signup and view all the answers

    How does the structure of amylopectin differ from amylose?

    <p>Amylopectin includes both linear chains and branch points.</p> Signup and view all the answers

    What role does storing carbohydrates in the form of polysaccharides play regarding cellular osmolarity?

    <p>It decreases the total cellular osmolarity.</p> Signup and view all the answers

    What is the average frequency of branch points in amylopectin?

    <p>Every 25 glucose units</p> Signup and view all the answers

    Which polysaccharide is recognized as the primary form of glucose storage in animals?

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

    Which of the following is NOT true regarding amylose?

    <p>It can have multiple branch points.</p> Signup and view all the answers

    What type of molecules can polysaccharides be assembled from?

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

    What is the primary structural difference between glycogen and amylopectin?

    <p>Glycogen has more branched structures.</p> Signup and view all the answers

    What is the molecular formula for a disaccharide formed from two monosaccharides?

    <p>Cn(H2O)n-1</p> Signup and view all the answers

    Which of the following describes the effect of glycosidic bonds on monosaccharide units?

    <p>They lock monosaccharides in cyclic form.</p> Signup and view all the answers

    How does the branching of glycogen affect its function?

    <p>It allows for rapid mobilization of glucose units.</p> Signup and view all the answers

    How does the molecular formula change as carbohydrates form larger structures?

    <p>The formula decreases in hydrogen and oxygen counts.</p> Signup and view all the answers

    Why can't animals digest cellulose?

    <p>They lack the enzymes to hydrolyze ẞ-1,4-glycosidic bonds.</p> Signup and view all the answers

    What defines an a-1,4-glycosidic bond?

    <p>Linkage between carbon 1 and carbon 4 with a α configuration.</p> Signup and view all the answers

    What type of bond links the glucose units in cellulose?

    <p>Beta-1,4-glycosidic bonds.</p> Signup and view all the answers

    Which property of cellulose allows for its structural role in plant cell walls?

    <p>Its linear chains of glucose linked by β-1,4-glycosidic bonds.</p> Signup and view all the answers

    What happens to a monosaccharide's anomeric configuration after it participates in a glycosidic bond?

    <p>It becomes fixed and cannot open to linearize.</p> Signup and view all the answers

    What is the role of glycogenin in glycogen structure?

    <p>Providing an anchor for glycogen chains.</p> Signup and view all the answers

    In the context of carbohydrate structure, what does the term 'branches' refer to?

    <p>Multiple glycosidic bonds to other monosaccharides.</p> Signup and view all the answers

    How do animals that consume cellulose primarily digest it?

    <p>With the help of symbiotic microflora.</p> Signup and view all the answers

    Which configuration is associated with a ẞ-2,6-glycosidic bond?

    <p>Çarbon 2 of a cyclic ketose linked to carbon 6.</p> Signup and view all the answers

    Which statement accurately reflects the characteristics of complex carbohydrates?

    <p>They can include multiple branches from a single monosaccharide.</p> Signup and view all the answers

    What type of end does glycogen lack, which is present in amylopectin?

    <p>A free reducing end.</p> Signup and view all the answers

    What is required for a carbohydrate to form a glycosidic bond?

    <p>An anomeric carbon must be free</p> Signup and view all the answers

    What distinguishes reducing sugars from nonreducing sugars?

    <p>Reducing sugars have free anomeric carbons</p> Signup and view all the answers

    During the Tollens test, which group is primarily responsible for reducing silver ions?

    <p>Aldehyde group</p> Signup and view all the answers

    What happens to the aldehyde group of an aldose during oxidation?

    <p>It is converted to a carboxylic acid</p> Signup and view all the answers

    Which statement is true regarding trehalose?

    <p>Both anomeric carbons are involved in glycosidic bonds</p> Signup and view all the answers

    What defines the reducing end of a complex carbohydrate?

    <p>It terminates with an anomeric carbon</p> Signup and view all the answers

    Which sugar can act as a reducing sugar despite having a ketone group?

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

    How is the configuration of a glycosidic bond in trehalose specified?

    <p>By combining both anomeric carbon configurations</p> Signup and view all the answers

    What structural difference exists between maltose and cellobiose?

    <p>They differ in the orientation of the glycosidic linkage.</p> Signup and view all the answers

    What type of glycosidic bond is present in sucrose?

    <p>a-1,β-2-glycosidic bond</p> Signup and view all the answers

    Which monosaccharide is in the pyranose form in sucrose?

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

    What is the main reason animals cannot digest cellobiose?

    <p>The orientation of its glycosidic bond is different.</p> Signup and view all the answers

    Why do humans experience lactose intolerance?

    <p>They do not produce enough lactase enzyme.</p> Signup and view all the answers

    What is the relationship between lactose and cellobiose?

    <p>They have different glycosidic bond orientations.</p> Signup and view all the answers

    What happens to the anomeric carbons when forming sucrose?

    <p>They flip along their vertical axes to align.</p> Signup and view all the answers

    Which enzyme is responsible for digesting lactose in humans?

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

    Study Notes

    Introduction to Complex Carbohydrates

    • Monosaccharides combine to form more complex carbohydrates via glycosidic bonds.
    • Disaccharides, trisaccharides, and polysaccharides are formed.
    • Glycans are another name for polysaccharides, often chains with multiple branch points.
    • Carbohydrates can form glycosidic bonds with proteins, lipids, and nitrogenous bases.
    • This modification can change the molecules.

    Glycosidic Bonds

    • A glycosidic bond is a chemical linkage between a carbohydrate's anomeric carbon and another molecule's nucleophilic atom.
    • The other molecule can be another carbohydrate, a protein, a lipid, or a nucleoside.
    • Glycosidic bond formation is a condensation reaction, releasing water.
    • The reaction can be reversed by hydrolysis.
    • Monosaccharides become monosaccharide residues (units) after glycosidic bond formation.

    Changes in Molecular Formulas

    • Disaccharides have the formula Cn(H2O)n-1.
    • Trisaccharides have the formula Cn(H2O)n-2.
    • Each additional monosaccharide in a chain reduces the water component.

    Concept Check 7.7

    • The molecular formula for a tetrasaccharide formed from one glucose (C6H12O6), one ribose (C5H10O5), one erythrose (C4H8O4), and one fructose (C6H12O6) molecule is C18H32O16.

    Glycosidic Bond Formation

    • The acetal or ketal is formed when a hemiacetal (or hemiketal) carbon from one monosaccharide condensates with a hydroxyl on another.
    • The resultant molecule is locked in a cyclic form.

    Reducing and Nonreducing Sugars

    • Free anomeric carbons are reducing sugars as they can reduce silver ions.
    • Nonreducing sugars have all anomeric carbons involved in glycosidic bonds.
    • Reducing sugars are those with a free anomeric carbon that can be involved in a redox reaction.
    • Nonreducing sugars cannot react.

    Glycosidic Bonds Between Carbohydrates and Noncarbohydrates

    • Glycoproteins and glycolipids are important examples of these types of bonds.
    • Glucose units can link with other molecules, forming glycoproteins and glycolipids.
    • Viruses or pathogens often use glycoproteins as a first step during infection.

    Disaccharides Summary

    • Maltose is a disaccharide formed from two glucose units linked by an α-1,4-glycosidic bond. Animals can digest it.
    • Cellobiose is similar to maltose, but with a β-1,4-glycosidic bond. Animals cannot digest it.
    • Sucrose has a glucose and a fructose unit linked by an α-1,β-2 glycosidic bond.

    Polysaccharides Summary

    • Starch is entirely glucose, and composed of amylose (linear) and amylopectin (branched).
    • Glycogen is the primary energy storage in animals and is even more branched than amylopectin.
    • Cellulose is also a glucose polymer, but its β-1,4-glycosidic linkages cannot be broken down by most enzymes thus, is indigestible to most animals.

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