Question

Differentiate between the structures of D-glucose and D-fructose.

Hint:

Glucose = aldohexose; Fructose = ketohexose. Both are hexoses but differ in functional groups.

Answer 1

Step 1: D-Glucose.
It is an aldohexose (6-carbon sugar with an aldehyde group at C-1). Open-chain form: \(\text{CH}_2\text{OH}-(CHOH)_4-CHO\). In cyclic form, it forms a pyranose ring.
Step 2: D-Fructose.
It is a ketohexose (6-carbon sugar with a ketone group at C-2). Open-chain form: \(\text{CH}_2\text{OH}-C=O-(CHOH)_3-CH_2\text{OH}\). In cyclic form, it forms a furanose ring.
Step 3: Key Difference.
Glucose has an aldehyde (aldohexose), Fructose has a ketone (ketohexose).