Question

What kind of sugars are these, aldose or ketose?

Short answer

• Glucose and galactose are aldoses.
• Fructose is a ketose.

Step-by-step solution

Introduction

Monosaccharides

• Simple sugars are known as monosaccharides.
• The suffix -ose is found at the end of most monosaccharide names.
• It could be aldose or ketose.
• They can be trioses, pentoses, or hexoses, depending on the number of carbons in the sugar.
• Example - glucose, galactose, fructose.

Explanation

Aldose

• If the monosaccharide has an aldehyde group (R-CHO), it is an aldose.
• Aldoses have a carbonyl group at the end of the carbon chain.
• Glucose andgalactose contain an aldehyde group, so they are aldoses.

Ketose

• If the monosaccharide has a ketone group ( RC(=O)R'), it is a ketose.

• ketoses have a carbonyl group in the middle of the carbon chain.

• Fructose contains a ketone group, so it is a ketose.