Carbohydrate Stereochemistry Diastereomers and Enantiomers

This video tutorial covers the stereochemistry of carbohydrates, focusing on epimers, anomers, diastereomers, and enantiomers. It explains how these stereochemical relationships differ and provides examples using glucose and other sugars. The tutorial emphasizes the importance of recognizing these relationships in biochemistry, even if determining them is not always necessary.

What is the key difference between epimers and anomers?

• Epimers are not stereoisomers, anomers are.

• Epimers differ at one stereocenter, anomers differ at the anomeric carbon.

• Epimers differ at multiple stereocenters, anomers differ at one.

• Epimers and anomers are identical.

Which of the following best describes diastereomers?

• They are identical in structure.

• They differ at multiple but not all stereocenters.

• They differ at one stereocenter.

• They differ at all stereocenters.

How do glucose and idose differ in terms of stereochemistry?

• They differ at three out of five stereocenters.

• They differ at all stereocenters.

• They are identical.

• They differ at only one stereocenter.

What is the relationship between glucose and galactose?

• They are epimers.

• They are diastereomers.

• They are enantiomers.

• They are identical.

What defines enantiomers in terms of stereochemistry?

• They are identical.

• They differ at every stereocenter.

• They differ at multiple but not all stereocenters.

• They differ at one stereocenter.

Which isomer of glucose is biologically active in humans?

• Both D and L-glucose

• D-glucose

• Neither D nor L-glucose

• L-glucose

What is a hexopyranose?

• A carbohydrate with six carbons and a six-membered ring.

• A carbohydrate with five carbons.

• A carbohydrate with seven carbons.

• A carbohydrate with six carbons and a five-membered ring.

How many D-isomers exist for hexopyranoses?

• Six

• Four

• Eight

• Ten

Why are L-carbohydrates not typically observed in biology?

• They are identical to D-carbohydrates.

• They are not used by organisms.

• They are toxic.

• They are unstable.

Which of the following is NOT a stereochemical relationship discussed?

• Anomers

• Constitutional isomers

• Epimers

• Diastereomers