Answer the following questions about the eight aldopentoses:
a. Which are enantiomers?
b. Which are C-2 epimers?

Verified step by step guidance

1. Identify the eight aldopentoses: D-Ribose, D-Arabinose, D-Xylose, D-Lyxose, L-Ribose, L-Arabinose, L-Xylose, L-Lyxose.
2. Understand that enantiomers are non-superimposable mirror images. For aldopentoses, D and L forms of the same sugar are enantiomers.
3. List the enantiomer pairs: D-Ribose and L-Ribose, D-Arabinose and L-Arabinose, D-Xylose and L-Xylose, D-Lyxose and L-Lyxose.
4. Recognize that C-2 epimers differ only at the second carbon atom.
5. Identify the C-2 epimer pairs: D-Ribose and D-Arabinose, L-Ribose and L-Arabinose.

Key Concepts

Aldopentoses

Aldopentoses are a class of monosaccharides that contain five carbon atoms and an aldehyde functional group. They are important in biochemistry and can exist in various stereoisomeric forms. The most common aldopentoses include ribose and arabinose, which play crucial roles in nucleic acids and metabolism.

Enantiomers

Enantiomers are a type of stereoisomer that are non-superimposable mirror images of each other. They typically arise in molecules that contain one or more chiral centers, leading to two distinct configurations. In the context of aldopentoses, identifying enantiomers involves recognizing pairs of sugars that differ at all chiral centers.

Epimers

Epimers are a specific type of diastereomer that differ in configuration at only one chiral center. In aldopentoses, C-2 epimers refer to sugars that have the same structure except for the orientation of the hydroxyl group at the second carbon atom. Understanding epimerism is essential for distinguishing between closely related sugars and their biological functions.