Biochemistry : Identifying Specific Carbohydrate Structures

Study concepts, example questions & explanations for Biochemistry

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Example Questions

Example Question #11 : Identifying Specific Carbohydrate Structures

Which of the following is a storage polysaccharide of plants?

Possible Answers:

Cellulose

Maltose

Glycogen

Starch

Amylopectin

Correct answer:

Starch

Explanation:

Amylopectin & amylose are joined to make starch. Cellulose is found in the cell wall of plant cells. Glycogen and maltose are not found in plants.

Example Question #21 : Identification By Structure

Identify the given structure.

D galactose

Possible Answers:

L-galactose

D-galactose

L-glucose

D-sucrose

D-glucose

Correct answer:

D-galactose

Explanation:

D-galactose is an aldohexose. Aldo indicates the aldehyde at the first carbon and hexose indicates a six-carbon sugar. The D-isomer is determined by the orientation of the highest number asymmetric carbon, which has a hydroxyl group pointin to the right in this Fischer projection.

Example Question #22 : Identification By Structure

Identify the given structure.

D glucose

Possible Answers:

D-glucose

D-fructose

D-galactose

D-gulose

D-altrose

Correct answer:

D-glucose

Explanation:

D-glucose is an aldohexose, one of the most important carbohydrates in biochemistry. Aldo indicates the aldehyde at the first carbon. Hexose indicates a six-carbon sugar. The D-isomer is determined by the orientation of the highest number asymmetric carbon, which has a hydroxyl group pointing to the right in the Fischer projection.

Example Question #23 : Identification By Structure

Identify the given structure.

D fructose

Possible Answers:

L-fructose

D-fructose

D-sorbose

D-xyulose

D-tagatose

Correct answer:

D-fructose

Explanation:

D-fructose is a ketohexos. Keto indicates the ketone present on carbon 2 and hexose indicates a six-carbon sugar. The D-isomer is determined by the orientation of the highest number asymmetric carbon, which has the hydroxyl group oriented to the right in the Fischer projection.

Example Question #11 : Identifying Specific Carbohydrate Structures

Identify the given structure.

D mannose

Possible Answers:

D-gulose

D-allose

D-glucose

D-alrose

D-mannose

Correct answer:

D-mannose

Explanation:

D-mannose is an aldohexose. Aldo indicates the aldehyde on the first carbon and the hexose indicates a six-carbon sugar. The D-isomer is determined by the orientation of the highest number asymmetric carbon, which has a hydroxyl group pointing to the right in the Fischer projection.

Example Question #15 : Identifying Specific Carbohydrate Structures

Identify the given structure.

D ribose

Possible Answers:

D-ribulose

D-glucose

D-mannose

D-ribose

D-sucrose

Correct answer:

D-ribose

Explanation:

D-ribose is an aldopentose. Aldo indicates the aldehyde on the first carbon and the pentose indicates a five-carbon sugar. The D-isomer is determined by the orientation of the highest number asymmetric carbon, which has a hydroxyl group pointing to the right in the Fischer projection.

Example Question #16 : Identifying Specific Carbohydrate Structures

Identify the given structure.

D sorbose

Possible Answers:

L-sorbose

D-sorbose

D-glucose

L-fructose

D-fructose

Correct answer:

D-sorbose

Explanation:

The pictured ketohexose is D-sorbose. Keto indicates the ketone present on carbon number two and hexose indicates a six-carbon sugar. The D-isomer is determined by the orientation of the highest number asymmetric carbon, which has a hydroxyl group pointing to the right in the Fischer projection.

Example Question #17 : Identifying Specific Carbohydrate Structures

Identify the carbohydrate class of the given molecule.

D fructose

Possible Answers:

Aldohexose

Ketohexose

Ketopentose

Ketalhexose

Aldopentose

Correct answer:

Ketohexose

Explanation:

The structure is of a ketohexose. Keto- refers to the ketone at the second carbon and hexose refers to a carbohydrate with six carbons.

Example Question #18 : Identifying Specific Carbohydrate Structures

Identify the carbohydrate class of the given molecule.

D galactose

Possible Answers:

Aldohexose

Ketopentose

Aldopentose

Hemiketose

Ketohexose

Correct answer:

Aldohexose

Explanation:

The structure is of an aldohexose. Aldo- refers to the aldehyde at the first carbon, and the hexose refers to a carbohydrate with six carbons.

Example Question #19 : Identifying Specific Carbohydrate Structures

Identify the carbohydrate class of the given molecule.

D ribose

Possible Answers:

Ketohexose

Aldopentose

Ketopentose

Aldoquintos

Aldohexose

Correct answer:

Aldopentose

Explanation:

The structure is an aldopentose. Aldo- refers to the aldehyde at the first carbon and pentose refers to a carbohydrate with five carbons.

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