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Example Questions
Example Question #1 : Identifying Specific Carbohydrate Structures
Which if the following statements about glucose is false?
In an aqueous solution, glucose can be found in open-chain, pyranose, or furanose form
It has the same molecular mass as fructose
None of the other answers is false.
It cannot isomerize into fructose
The anomeric effect has an influence on glucose’s mutarotation.
It cannot isomerize into fructose
Glucose and fructose have the same constituent atoms, so they have the same molecular mass (about ). Glucose exists in aqueous solution in an equilibrium of open-chain and several cyclic isomer forms, the most common of which is pyranose, but also one of which is furanose. Upon forming a ring structure, glucose may take one of two anomers, alpha or beta. The relative proportion of the mutarotated beta form is increased versus the alpha form because the beta anomer is such that all non hydrogen substituents are in the equitorial position. Glucose can indeed be isomerized into fructose; this is part of glycolysis.
Example Question #1 : Identifying Specific Carbohydrate Structures
The molecule sucrose is shown below
What is the full name for this molecule?
-D-glucopyranosyl-(1
2)-
-D-fructopyranoside
-D-glucopyranosyl-(1
4)-
-D-fructofuranoside
None of these
-D-glucopyranosyl-(1
2)-
-D-fructofuranoside
-D-glucopyranosyl-(1
2)-
-D-fructofuranoside
-D-glucopyranosyl-(1
2)-
-D-fructofuranoside
Sucrose is the molecule shown below(in Haworth projection).
We recognize that it's a disaccharide, and that the first molecule is -D-glucopyranose. The bond to the second monosaccharide (fructose) is tricky because the glycosidic bond is going to the anomeric carbon of fructose. Therefore, this is a 1-2 linkage. Finally, since the anomeric carbon of fructose is pointing in the same direction as the 6th carbon, this is a
-D-fructopyranose.
Example Question #62 : Identifying Biochemical Molecules
Which of the following sugars is lactose?
Beta-D-glucopyranosyl-1,4-D-glucopyranose
Beta-L-galactopyranosyl-1,4-D-glucopyranose
Alpha-D-galactopyranosyl-(1,4)-D-glucopyranose
Beta-D-galactopyranosyl-(1,4)-D-glucopyranose
Beta-D-galactopyranosyl-(1,4)-D-glucopyranose
Lactose is made by joining a galactose to a glucose via a
carbon pathway. Both sugars are D-sugars.
Example Question #12 : Identification By Structure
What is the difference between two carbohydrates that are epimers and two carbohydrates that are anomers?
The number of carbons that have differences in configuration
The number of rings
The shape of the ring
The location of the change in configuration
The location of the change in configuration
A set of anomers will differ in the configurations of their carbonyl carbons only while a set of epimers will differ in configuration in only one carbon that is not the carbonyl carbon.
Example Question #2 : Identifying Specific Carbohydrate Structures
Glucose and galactose share a chemical formula and are known as epimers.
What is the difference between glucose and galactose?
Galactose is spread further apart than glucose
Glucose is bigger than galactose
Galactose is a ketose
They differ in configuration around the fourth carbon
They differ in configuration around the fourth carbon
As a pair of epimers, this means that both glucose and galactose are the same in configuration in all carbons except for one non-carbonyl carbon. To differ in the configuration of the carbonyl carbon makes an anomer not an epimer. Both glucose and galactose are aldoses.
Example Question #1 : Identifying Specific Carbohydrate Structures
The following are the common substrates, enzymes and the associated products.
Although cellulose provides the same carbohydrates as maltose, it cannot be broken down by humans. What type of linkage prevents humans from breaking down the polysaccharide?
Beta-1,6 glycosidic bond
Alpha-1,6 glycosidic bond
Alpha-1,4 glycosidic bond
None of these
Beta-1,4 glycosidic bond
Beta-1,4 glycosidic bond
The beta-1,4 glycosidic bond is not a substrate for any human enzymes, and is thus left untreated.
Example Question #1 : Identifying Specific Carbohydrate Structures
Which of the following enzymes is correctly paired with its products and substrates?
An easy way to distinguish the substrate and the product from the enzyme is that the enzyme will end in "ase". The following are the common substrates, enzymes and the associated products.
Example Question #8 : Identifying Specific Carbohydrate Structures
Which of the following enzymes is correctly paired with its products and substrates?
An easy way to distinguish the substrate nd the product from the enzyme is that the enzyme will end in "ase". The following are the common substrates, enzymes and the associated products.
Example Question #9 : Identifying Specific Carbohydrate Structures
Which of the following enzymes is correctly paired with its products and substrates?
An easy way to distinguish the substrate and the product from the enzyme is that the enzyme will end in "ase". The following are the common substrates, enzymes and the associated products.
Example Question #10 : Identifying Specific Carbohydrate Structures
Which of the following enzymes is correctly paired with its products and substrates?
All of these
An easy way to distinguish the substrate and the product from the enzyme is that the enzyme will end in "ase". The following are the common substrates, enzymes and the associated products.
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