Biochemistry Chapter 10 Flashcards
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Questions and Answers

D-Glucose and L-glucose are

  • Epimers
  • Enantiomers (correct)
  • Diastereoisomers
  • Anomers
  • The furanose form of fructose is generated by the formation of a hemiketal, involving the attack of the hydroxyl group on

  • C-5 by C-2 (correct)
  • C-6 by C-1
  • C-6 by C-2
  • C-2 by C-6
  • If the resulting anomeric alcohol group is above the plane of the sugar, the structure is known as

  • The epimeric stereoisomer
  • The α-anomer
  • The L-enantiomer
  • The D-enantiomer
  • The β-anomer (correct)
  • Once formed, the α- and β-forms of D-glucose are

    <p>Interconvertible only through a linear, noncyclic intermediate with which they are both in equilibrium</p> Signup and view all the answers

    Why does glucose yield a positive test with cupric ions, such as those found in Fehling's solution, whereas sucrose does not?

    <p>Glucose is a reducing sugar in equilibrium with its free aldehyde form, whereas sucrose is not</p> Signup and view all the answers

    Advanced glycation end products are

    <p>Products of reactions between reducing sugars and free amino groups</p> Signup and view all the answers

    Human blood groups (ABO) are the result of

    <p>Differing glycosyltransferases</p> Signup and view all the answers

    The amino acid R groups that serve as the sites for carbohydrate attachment include

    <p>Hydroxyl groups</p> Signup and view all the answers

    Name the types of carbohydrates you need to determine whether they are monosaccharides, disaccharides, or polysaccharides.

    <p>Monosaccharides, disaccharides, polysaccharides</p> Signup and view all the answers

    Classify the sugars as either aldoses or ketoses.

    <p>Aldoses and ketoses</p> Signup and view all the answers

    Classify each monosaccharide according to the position of the carbonyl group and the number of carbon atoms in the molecule.

    <p>Classification based on carbonyl position and carbon count.</p> Signup and view all the answers

    Which of the terms explains the relationship between the two compounds?

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

    Analyze the following pair of compounds. Which of the terms explains the relationship between the two compounds?

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

    Which structure is a D-2-ketotetrose?

    <p>Identification required</p> Signup and view all the answers

    Draw the Fischer projections of the four aldotetroses.

    <p>D-threose, L-threose, D-erythrose, L-erythrose</p> Signup and view all the answers

    Which Haworth projection corresponds to the β-pyranose form of the Fischer projection?

    <p>Identification required</p> Signup and view all the answers

    Select the Fischer projection that is the open chain version of the Haworth projection.

    <p>Identification required</p> Signup and view all the answers

    Name the monosaccharides in the images by placing the appropriate terms.

    <p>Identification required</p> Signup and view all the answers

    Complete the Haworth projection of α-D-galactose by placing labels on the pyranose ring.

    <p>Label placement required</p> Signup and view all the answers

    Which of the chair conformations is represented by the Haworth projection?

    <p>Identification required</p> Signup and view all the answers

    Draw the α and β forms of glucose by placing the groups in the appropriate positions.

    <p>Graphical representation required</p> Signup and view all the answers

    Select all the monosaccharides that are correctly paired with their class.

    <p>Fructose : Hexose Ketose</p> Signup and view all the answers

    The specific rotations of the α and β anomers of D-glucose are +112° and +18.7°, respectively. Calculate the proportions of the α and β anomers at equilibrium.

    <p>α=0.36, β=0.64</p> Signup and view all the answers

    Which statements about reducing sugars are true?

    <p>A disaccharide with its anomeric carbons joined by the glycosidic linkage cannot be a reducing sugar</p> Signup and view all the answers

    Which methods could be used to hydrolyze sucrose to invert sugar nonenzymatically in your kitchen?

    <p>Boil the sucrose solution in water</p> Signup and view all the answers

    Identify the disaccharide formed when UDP-galactose is combined with another glucose unit.

    <p>Identification required</p> Signup and view all the answers

    Label the Venn diagram for maltose and sucrose.

    <p>Label placement required</p> Signup and view all the answers

    Linking together one glucose, one mannose, and one galactose molecule can form how many different trisaccharides?

    <p>12,288</p> Signup and view all the answers

    Complete the passage about raffinose.

    <p>Raffinose is composed of D-galactose, D-glucose, and D-fructose</p> Signup and view all the answers

    Determine whether each phrase describes starch, glycogen, or cellulose.

    <p>Classification required</p> Signup and view all the answers

    Why is cellulose not a source of nutrients for humans?

    <p>Humans, and most vertebrates, lack the enzyme cellulase</p> Signup and view all the answers

    Label blood types O and A with the correct monosaccharides.

    <p>Label placement required</p> Signup and view all the answers

    Which of the structures are examples of glycosaminoglycans?

    <p>Identification required</p> Signup and view all the answers

    ___ are the proteins involved in recognition of specific oligosaccharide structures.

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

    Identify the statement that describes how acarbose and miglitol decrease glucose absorption after a meal.

    <p>Acarbose and miglitol bind to the α-glucosidase active site and prevent the enzyme from binding to oligosaccharides</p> Signup and view all the answers

    Study Notes

    Carbohydrates and Their Structures

    • D‑Glucose and L‑glucose are classified as enantiomers, sharing the same molecular formula but differing in spatial arrangement.
    • The furanose form of fructose arises from a reaction where the hydroxyl group on C‑2 attacks C‑5, creating a hemiketal structure.
    • Formation of pyranose and furanose sugar arrangements produces a new chiral center, leading to the α and β forms; the β-anomer has the anomeric alcohol group above the sugar plane.
    • α- and β-forms of D‑glucose interconvert via a linear, noncyclic intermediate, maintaining an equilibrium state, rather than converting directly.
    • Glucose acts as a reducing sugar with a free aldehyde form, which allows it to react positively with cupric ions, a contrast to non-reducing sucrose.

    Glycation and Blood Groups

    • Advanced glycation end products result from reactions between reducing sugars and amino groups, impacting protein function.
    • Human blood groups (ABO) originate from variations in glycosyltransferases, which modify sugar attachment.
    • Glycoprotein structures rely on hydroxyl groups found in R groups for carbohydrate attachment.

    Sugar Classification

    • Monosaccharides can be classified by their carbonyl group (aldehyde or ketone) and carbon count, with aldoses featuring an aldehyde on C1 and ketoses typically having a ketone on C2.
    • Epimers and anomers are specific types of diastereomers distinguished by their configuration at one asymmetric carbon or at the anomeric carbon, respectively.

    Chemical Reactions and Properties

    • Only certain monosaccharides are reducing sugars, capable of forming carboxylic acids upon oxidation; D‑mannose is a notable example.
    • To convert sucrose to invert sugar nonenzymatically, methods include boiling the solution or adding acetic acid in warm water.

    Structural Complexity

    • A combination of glucose, mannose, and galactose can yield numerous trisaccharides due to structural permutations, amounting to 12,288 potential configurations.
    • Raffinose consists of D-galactose, D-glucose, and D-fructose; it is nonreducing due to glycosidic bonds preventing participation in oxidation reactions.

    Polysaccharides and Digestibility

    • Cellulose is indigestible for humans because vertebrate enzymes hydrolyze α-1,4 linkages, whereas cellulose's β-linkages resist this process; thus, humans lack the enzyme cellulase required for its digestion.

    Oligosaccharide Recognition

    • Lectins are essential proteins that recognize specific oligosaccharide structures in biological systems, aiding in cell communication and interaction.

    Pharmaceutical Applications

    • Acarbose and miglitol inhibit glucose absorption by blocking the active site of α-glucosidase, preventing oligosaccharide breakdown in the intestines, which can aid in managing blood sugar levels post-meal.

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    Test your knowledge of key concepts from Chapter 10 of Biochemistry with these flashcards. Focus on sugars, their structures, and stereochemistry is essential for understanding biochemical processes. Challenge yourself and see how well you grasp these important definitions.

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