Recent

  • Show all results for ""
Carbohydrate Classification and Structure
45 Questions
100 Views

Carbohydrate Classification and Structure

Created by
@PromisingStonehenge

Questions and Answers

What is the difference between aldose and ketose?

  • Ketose has an aldehyde group.
  • Aldose has an aldehyde group. (correct)
  • Aldose has a ketone group.
  • Both have the same structure.

    • What are the three most abundant hexoses?

  • D-glucose, D-galactose, D-fructose (correct)
  • D-glucose, D-fructose, D-mannose
  • D-galactose, D-mannose, L-fructose
  • D-glucose, L-galactose, D-fructose

    • What is an enantiomer?

    Non-superimposable mirror images

    Which carbon of an aldopentose determines whether the pentose has a D or L configuration?

    <p>Carbon 4</p> Signup and view all the answers

    What is an amino sugar?

    <p>One or more -OH groups are replaced by -NH2 groups</p> Signup and view all the answers

    Name three amino sugars commonly found in nature.

    <p>D-glucosamine, D-galactosamine, N-acetyl-D-glucosamine</p> Signup and view all the answers

    What is the structure difference between pyranose and furanose?

    <p>Pyranose has a 6-membered ring.</p> Signup and view all the answers

    Are α-D-glucose and β-D-glucose enantiomers?

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

    How are chair conformations a more accurate representation of molecular shapes of hexopyranoses than Haworth projections?

    <p>Chair conformation shows a puckered ring, which is more stable than the planar hexagon of Haworth projections.</p> Signup and view all the answers

    What is the specific rotation of β-D-glucose if the specific rotation of α-D-glucose is +112.2?

    <p>-112.2</p> Signup and view all the answers

    Define glycoside.

    <p>A cyclic acetal of a monosaccharide</p> Signup and view all the answers

    Do glycosides undergo mutarotation?

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

    What does a B-1,4 glycosidic bond indicate?

    <p>The configuration at the anomeric carbon is beta and bonded to carbon four of the second monosaccharide.</p> Signup and view all the answers

    What is the structural difference between oligosaccharides and polysaccharides?

    <p>Oligosaccharides have 6 to 10 monosaccharide units; polysaccharides have more than 10.</p> Signup and view all the answers

    What is the major structural difference between amylose and amylopectin?

    <p>Amylose is unbranched; amylopectin has a branched structure.</p> Signup and view all the answers

    Why is cellulose insoluble in water?

    <p>Strong hydrogen bonding in the fiber is not overcome by intermolecular forces.</p> Signup and view all the answers

    Carbs in foods have different weights.

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

    What is the difference in the glycosidic bonds in starch and cellulose?

    <p>Starch has α-glycosidic bonds; cellulose has β-glycosidic bonds.</p> Signup and view all the answers

    What is the structural difference between glucose and galactose?

    <p>Configuration at carbon C4 of the ring.</p> Signup and view all the answers

    Can galactose be converted to glucose in the body? If so, how?

    <p>Yes, through inversion of configuration via a specific enzyme.</p> Signup and view all the answers

    α-D-glucose and β-D-glucose are

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

    How can a carbohydrate be defined?

    <p>A molecule that is an aldehyde or ketone with more than one hydroxyl group.</p> Signup and view all the answers

    What is a carbohydrate that gives two molecules when completely hydrolyzed?

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

    A glycosidic bond between two monosaccharides can also be classified as a(n)

    <p>ether bond</p> Signup and view all the answers

    What defines a glycosidic bond?

    <p>A bond formed between an anomeric carbon atom and any -OR group.</p> Signup and view all the answers

    What does a hemiacetal linkage consist of?

    <p>A carbon atom bonded to both an -OH and an -OR group.</p> Signup and view all the answers

    A monosaccharide that consists of 5 carbon atoms and has a ketone group is classified as a(n)

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

    Cellulose is not digestible by humans because it contains glucose units linked by ________-glycosidic bonds.

    <p>β-1,4</p> Signup and view all the answers

    Common reducing reactions of monosaccharides are due to?

    <p>The presence of a carbonyl group, usually on the #1 carbon atom.</p> Signup and view all the answers

    Galactose is a product of enzymatic hydrolysis of?

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

    How many stereoisomers of an aldotetrose can exist?

    <p>4</p> Signup and view all the answers

    In the L-isomer of a Fischer projection of a monosaccharide, the -OH group furthest from the carbonyl is written?

    <p>On the left of the bottom chiral carbon.</p> Signup and view all the answers

    Ketoses can act as reducing sugars in basic solution because?

    <p>The ketone is converted to an aldehyde by keto-enol tautomerization.</p> Signup and view all the answers

    Pyranose rings are usually most stable when the ring adopts a ________ conformation with the bulkiest ring substituents in ________ positions.

    <p>chair, equatorial</p> Signup and view all the answers

    The breakdown of glucose to chemical energy for the cells to do work is an example of?

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

    The conversion between α and β anomers is called?

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

    The oxidation of monosaccharides produces?

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

    This functional group is known as a(n) ester.

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

    Under acid hydrolysis conditions, starch is converted to?

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

    What type of bond links the monomers of a polysaccharide?

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

    Which group of carbohydrates cannot be hydrolyzed to give smaller molecules?

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

    Which of the following contains a β-1,4-glycosidic bond?

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

    Which sugar is NOT a reducing sugar?

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

    You have two bottles, each containing a white crystalline substance. How would you determine which bottle contains lactose and which contains sucrose?

    <p>Test for the ability to reduce Ag+. Only lactose will react.</p> Signup and view all the answers

    ________ of glucose leads to gluconic acid.

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

    Study Notes

    Carbohydrate Classification and Structure

    • Aldoses have an aldehyde carbonyl group; ketoses possess a ketone carbonyl group.
    • Most abundant hexoses are D-glucose, D-galactose (both aldoses), and D-fructose (a ketose).
    • Enantiomers are non-superimposable mirror images; they exhibit different properties.

    Configuration and Isomerism

    • Configuration at carbon 4 determines if an aldopentose has D or L configuration.
    • α-D-glucose and β-D-glucose are anomers, differing at anomeric carbon (carbon 1), but are not enantiomers.
    • There are 4 stereoisomers possible for an aldotetrose.

    Types of Sugars and Modifications

    • Amino sugars form when one or more -OH groups are replaced by -NH2; key examples include D-glucosamine, D-galactosamine, and N-acetyl-D-glucosamine.
    • Pyranose refers to a six-membered cyclic structure; furanose denotes a five-membered cyclic form.

    Glycosidic Bonds and Reactions

    • Glycosidic bonds form between the anomeric carbon (anomeric carbon to -OR group) and can be classified as ether bonds.
    • Cellulose contains β-1,4-glycosidic bonds, making it indigestible by humans; starch is linked by α-glycosidic bonds which are digestible.
    • Mutarotation refers to the conversion between α and β anomers.

    Stability and Structure of Sugars

    • Chair conformation provides a more accurate representation of hexopyranoses than Haworth projections due to the puckered structure and stability.
    • Specific rotation of a-D-glucose and b-D-glucose is +112.2° and -112.2° respectively.

    Hydrolysis and Enzymatic Reactions

    • Disaccharides yield two monosaccharide units upon hydrolysis; lactose hydrolysis yields galactose.
    • Under acid conditions, starch hydrolyzes to glucose, while oxidation of monosaccharides generates sugar acids.

    Reducing and Non-Reducing Sugars

    • Reducing sugars contain a free carbonyl group and include aldoses and some ketoses; sucrose is a non-reducing sugar.
    • Ketoses can act as reducing sugars in basic solutions via keto-enol tautomerization.

    Monosaccharide Features

    • Monosaccharides contain one carbonyl group and multiple hydroxyl groups; they cannot be hydrolyzed into smaller units.
    • The structure of glucose and galactose differs at carbon C4; conversion between them is through inversion of configuration facilitated by specific enzymes.

    Functional Groups and Bonds

    • An ester functional group consists of a carbon atom bonded to both an -OH and an -OR group.
    • Hemiacetals are characterized by a carbon atom linked to both an -OH and an -OR group.

    Summary of Carbohydrate Functions

    • Carbohydrate oxidation leads to energy for cellular function.
    • Glycosidic bonds link monomers in polysaccharides, and oligosaccharides consist of 6 to 10 monosaccharide units.
    • Multiple factors, including stereochemistry and bond types, influence the digestibility and properties of carbohydrates.

    Studying That Suits You

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

    Quiz Team

    Description

    This quiz examines the classification and structural characteristics of carbohydrates, focusing on aldoses and ketoses, stereoisomers, and types of sugars. It also covers glycosidic bonds and the formation of amino sugars. Test your understanding of these essential biochemical concepts.

    More Quizzes Like This

    Carbohydrate Structure: Sugars
    30 questions

    Carbohydrate Structure: Sugars

    BeneficentKeytar avatar
    BeneficentKeytar
    Molisch Test: Sugar Detection
    6 questions

    Molisch Test on Dilution: Sugar Detection Quiz and Flashcards

    OpulentSilver avatar
    OpulentSilver
    Reducing Sugars in Chemistry
    10 questions

    Reducing Sugars in Chemistry

    LighterTucson avatar
    LighterTucson
    الفرق بين السكرين والمانوز والغالاكتوز
    13 questions

    الفرق بين السكرين والمانوز والغالاكتوز

    ComplementaryHappiness avatar
    ComplementaryHappiness
    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser