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Questions and Answers
What is the difference between aldose and ketose?
What is the difference between aldose and ketose?
What are the three most abundant hexoses?
What are the three most abundant hexoses?
What is an enantiomer?
What is an enantiomer?
Non-superimposable mirror images
Which carbon of an aldopentose determines whether the pentose has a D or L configuration?
Which carbon of an aldopentose determines whether the pentose has a D or L configuration?
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What is an amino sugar?
What is an amino sugar?
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Name three amino sugars commonly found in nature.
Name three amino sugars commonly found in nature.
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What is the structure difference between pyranose and furanose?
What is the structure difference between pyranose and furanose?
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Are α-D-glucose and β-D-glucose enantiomers?
Are α-D-glucose and β-D-glucose enantiomers?
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How are chair conformations a more accurate representation of molecular shapes of hexopyranoses than Haworth projections?
How are chair conformations a more accurate representation of molecular shapes of hexopyranoses than Haworth projections?
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What is the specific rotation of β-D-glucose if the specific rotation of α-D-glucose is +112.2?
What is the specific rotation of β-D-glucose if the specific rotation of α-D-glucose is +112.2?
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Define glycoside.
Define glycoside.
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Do glycosides undergo mutarotation?
Do glycosides undergo mutarotation?
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What does a B-1,4 glycosidic bond indicate?
What does a B-1,4 glycosidic bond indicate?
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What is the structural difference between oligosaccharides and polysaccharides?
What is the structural difference between oligosaccharides and polysaccharides?
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What is the major structural difference between amylose and amylopectin?
What is the major structural difference between amylose and amylopectin?
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Why is cellulose insoluble in water?
Why is cellulose insoluble in water?
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Carbs in foods have different weights.
Carbs in foods have different weights.
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What is the difference in the glycosidic bonds in starch and cellulose?
What is the difference in the glycosidic bonds in starch and cellulose?
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What is the structural difference between glucose and galactose?
What is the structural difference between glucose and galactose?
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Can galactose be converted to glucose in the body? If so, how?
Can galactose be converted to glucose in the body? If so, how?
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α-D-glucose and β-D-glucose are
α-D-glucose and β-D-glucose are
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How can a carbohydrate be defined?
How can a carbohydrate be defined?
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What is a carbohydrate that gives two molecules when completely hydrolyzed?
What is a carbohydrate that gives two molecules when completely hydrolyzed?
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A glycosidic bond between two monosaccharides can also be classified as a(n)
A glycosidic bond between two monosaccharides can also be classified as a(n)
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What defines a glycosidic bond?
What defines a glycosidic bond?
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What does a hemiacetal linkage consist of?
What does a hemiacetal linkage consist of?
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A monosaccharide that consists of 5 carbon atoms and has a ketone group is classified as a(n)
A monosaccharide that consists of 5 carbon atoms and has a ketone group is classified as a(n)
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Cellulose is not digestible by humans because it contains glucose units linked by ________-glycosidic bonds.
Cellulose is not digestible by humans because it contains glucose units linked by ________-glycosidic bonds.
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Common reducing reactions of monosaccharides are due to?
Common reducing reactions of monosaccharides are due to?
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Galactose is a product of enzymatic hydrolysis of?
Galactose is a product of enzymatic hydrolysis of?
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How many stereoisomers of an aldotetrose can exist?
How many stereoisomers of an aldotetrose can exist?
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In the L-isomer of a Fischer projection of a monosaccharide, the -OH group furthest from the carbonyl is written?
In the L-isomer of a Fischer projection of a monosaccharide, the -OH group furthest from the carbonyl is written?
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Ketoses can act as reducing sugars in basic solution because?
Ketoses can act as reducing sugars in basic solution because?
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Pyranose rings are usually most stable when the ring adopts a ________ conformation with the bulkiest ring substituents in ________ positions.
Pyranose rings are usually most stable when the ring adopts a ________ conformation with the bulkiest ring substituents in ________ positions.
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The breakdown of glucose to chemical energy for the cells to do work is an example of?
The breakdown of glucose to chemical energy for the cells to do work is an example of?
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The conversion between α and β anomers is called?
The conversion between α and β anomers is called?
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The oxidation of monosaccharides produces?
The oxidation of monosaccharides produces?
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This functional group is known as a(n) ester.
This functional group is known as a(n) ester.
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Under acid hydrolysis conditions, starch is converted to?
Under acid hydrolysis conditions, starch is converted to?
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What type of bond links the monomers of a polysaccharide?
What type of bond links the monomers of a polysaccharide?
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Which group of carbohydrates cannot be hydrolyzed to give smaller molecules?
Which group of carbohydrates cannot be hydrolyzed to give smaller molecules?
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Which of the following contains a β-1,4-glycosidic bond?
Which of the following contains a β-1,4-glycosidic bond?
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Which sugar is NOT a reducing sugar?
Which sugar is NOT a reducing sugar?
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You have two bottles, each containing a white crystalline substance. How would you determine which bottle contains lactose and which contains sucrose?
You have two bottles, each containing a white crystalline substance. How would you determine which bottle contains lactose and which contains sucrose?
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________ of glucose leads to gluconic acid.
________ of glucose leads to gluconic acid.
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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.
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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.
