Biochemistry : Identifying Specific Carbohydrate Structures

Study concepts, example questions & explanations for Biochemistry

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Example Questions

Example Question #21 : Identifying Specific Carbohydrate Structures

Identify the carbohydrate class of the given molecule.

D ribulose

Possible Answers:

Aldopentose

Ketoquintos

Ketohexose

Ketopentose

Aldohexose

Correct answer:

Ketopentose

Explanation:

The structure is a ketopentose. Keto- refers to the ketone at the second carbon and pentose refers to a carbohydrate with five carbons.

Example Question #22 : Identifying Specific Carbohydrate Structures

Identify the given structure.

D glucose ring

Possible Answers:

L-galactose

D-glucose

L-glucose

D-fructose

D-galactose

Correct answer:

D-glucose

Explanation:

This ring structure is of D-glucose. The hydroxyl group on the first carbon (the carbon to the bottom right of the oxygenin the ring) can face either down (the alpha conformation) or up (the beta conformation). Note that the beta conformer is more thermodynamically stable since all the hydroxyl groups on the ring would be in the equitorial position, thus minimizing steric hinderance and intramolecular electrostatic repulsion.

Example Question #23 : Identifying Specific Carbohydrate Structures

Identify the given structure.

D fructose ring

Possible Answers:

D-galactose

D-glucose

D-fructose

D-mannose

D-ribose

Correct answer:

D-fructose

Explanation:

This is the ring/cyclic structure of D-fructose.

Example Question #301 : Biochemistry

Which of the following is the correct structure of a disaccharide?

Possible Answers:

Maltose = sucrose + fructose

Lactose = galactose + galactose

Maltose = glucose + glucose

Lactose = galactose + fructose

Sucrose = glucose + glucose

Correct answer:

Maltose = glucose + glucose

Explanation:

The correct structures of the disaccharides are:

Maltose = glucose + glucose

Sucrose = glucose + fructose

Lactose = glucose + galactose

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