Textbook Question
Isomaltose, obtained from the breakdown of starch, has the following Haworth structure:
d. Is this the α or β isomer of isomaltose?
Ch.13 Carbohydrates
Timberlake13th EditionChemistry: An Introduction to General, Organic, and Biological ChemistryISBN: 9780134421353
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Table of contents
- Ch.1 Chemistry in Our Lives11
- Ch.2 Chemistry and Measurements80
- Ch.3 Matter and Energy54
- Ch.4 Atoms and Elements51
- Ch.5 Nuclear Chemistry42
- Ch.6 Ionic and Molecular Compounds57
- Ch.7 Chemical Quantities and Reactions41
- Ch.8 Gases29
- Ch.9 Solutions51
- Ch.10 Acids and Bases and Equilibrium65
- Ch.11 Introduction to Organic Chemistry: Hydrocarbons78
- Ch.12 Alcohols, Thiols, Ethers, Aldehydes, and Ketones83
- Ch.13 Carbohydrates54
- Ch.14 Carboxylic Acids, Esters, Amines, and Amides90
- Ch.15 Lipids61
- Ch.16 Amino Acids, Proteins, and Enzymes84
- Ch.17 Nucleic Acids and Protein Synthesis83
- Ch.18 Metabolic Pathways and ATP Production67
Timberlake13th EditionChemistry: An Introduction to General, Organic, and Biological ChemistryISBN: 9780134421353Not the one you use?Change textbook
Chapter 13, Problem 57c
Melezitose, a carbohydrate secreted by insects, has the following Haworth structure:
c. Is melezitose a reducing sugar?
Verified step by step guidance1
Step 1: Understand the concept of a reducing sugar. A reducing sugar is a carbohydrate that can act as a reducing agent because it has a free aldehyde group (-CHO) or a free ketone group (-C=O) in its open-chain form. This property allows it to reduce other compounds, such as Benedict's reagent.
Step 2: Analyze the structure of raffinose. Raffinose is a trisaccharide composed of galactose, glucose, and fructose. In its structure, the glucose unit is linked to the galactose and fructose units through glycosidic bonds.
Step 3: Determine if the glucose unit in raffinose has a free anomeric carbon. The anomeric carbon is the carbon derived from the carbonyl group (C=O) in the open-chain form of the sugar. If this carbon is involved in a glycosidic bond, it is not free and cannot participate in redox reactions.
Step 4: Evaluate the fructose unit in raffinose. Fructose is a ketose sugar, and its anomeric carbon can also be involved in glycosidic bonding. If both the glucose and fructose units have their anomeric carbons involved in glycosidic bonds, raffinose will not have a free reducing end.
Step 5: Conclude whether raffinose is a reducing sugar. Based on the analysis, if all anomeric carbons in raffinose are involved in glycosidic bonds, it cannot act as a reducing sugar. This means raffinose is a non-reducing sugar.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Reducing Sugars
Reducing sugars are carbohydrates that can donate electrons to another chemical, typically due to the presence of a free aldehyde or ketone group. This property allows them to reduce other compounds, which is a key characteristic in various biochemical reactions. Common examples include glucose and fructose, which can participate in redox reactions.
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Ketoses as Reducing Sugars Concept 2
Raffinose Structure
Raffinose is a trisaccharide composed of galactose, glucose, and fructose. Its structure includes a galactose unit linked to a sucrose molecule, which is a combination of glucose and fructose. Understanding its structure is essential to determine its reactivity and whether it can act as a reducing sugar.
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Haworth Projection
The Haworth projection is a way of representing the cyclic structure of carbohydrates, showing the arrangement of atoms in a ring form. This representation helps visualize the orientation of hydroxyl groups and other substituents, which is crucial for understanding the chemical properties and reactivity of sugars, including whether they are reducing or non-reducing.
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Related Practice
Textbook Question
Melezitose, a carbohydrate secreted by insects, has the following Haworth structure:
a. Is melezitose a mono-, di-, or trisaccharide?
Textbook Question
Melezitose, a carbohydrate secreted by insects, has the following Haworth structure:
b. What monosaccharides are present in melezitose?
Textbook Question
What are the disaccharides and polysaccharides present in each of the following?
a. <IMAGE>
1
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Textbook Question
What are the disaccharides and polysaccharides present in each of the following?
a. <IMAGE>
Textbook Question
Identify each of the following pairs of Fischer projections as enantiomers or identical compounds:
a.