Q.Both deoxyribose and ribose belong to a class of sugars called:

Ribose and deoxyribose are fundamental monosaccharides, which are simple sugar units. The classification of these sugars is based on the number of carbon atoms present in their structure.

• Ribose, a component of RNA, contains five carbon atoms.
• Deoxyribose, a component of DNA, also contains five carbon atoms (specifically, it is 2-deoxyribose, meaning it lacks an oxygen atom at the second carbon position compared to ribose, but still has five carbons).

Sugars with five carbon atoms are collectively known as pentoses. Trioses have three carbon atoms, while hexoses have six carbon atoms (e.g., glucose, fructose). Polysaccharides are complex carbohydrates formed from many monosaccharide units linked together, not a class for individual simple sugars like ribose or deoxyribose.

Sugars, or carbohydrates, are essential biomolecules that serve various functions in living organisms, from energy storage to structural support. The simplest form of carbohydrates are monosaccharides, which are single sugar units. These monosaccharides are primarily classified based on the number of carbon atoms they contain.

Ribose and deoxyribose are two such monosaccharides that play incredibly vital roles in the molecular machinery of life. Ribose is a fundamental component of ribonucleic acid (RNA), which is involved in protein synthesis and gene expression. It is also a part of adenosine triphosphate (ATP), the primary energy currency of the cell. Deoxyribose, on the other hand, is the sugar component of deoxyribonucleic acid (DNA), the genetic material that carries hereditary information.

The key to classifying these sugars lies in counting their carbon atoms. Both ribose and deoxyribose are structured around a backbone of five carbon atoms. This specific number of carbons determines their classification within the broader category of monosaccharides.

Monosaccharides are named according to their carbon count:

• Trioses are sugars with three carbon atoms. An example is glyceraldehyde.
• Tetroses are sugars with four carbon atoms. An example is erythrose.
• Pentoses are sugars with five carbon atoms. Ribose and deoxyribose fall into this category.
• Hexoses are sugars with six carbon atoms. Common examples include glucose, fructose, and galactose.

Considering the options provided:

• (A) Trioses: This class refers to sugars with three carbon atoms. Ribose and deoxyribose have five carbons, so this is incorrect.
• (B) Hexoses: This class refers to sugars with six carbon atoms. While important sugars like glucose are hexoses, ribose and deoxyribose are not.
• (C) Pentoses: This class refers to sugars with five carbon atoms. Since both ribose and deoxyribose possess five carbon atoms, this is the correct classification.
• (D) Polysaccharides: This term refers to complex carbohydrates formed by linking many monosaccharide units together. Examples include starch, glycogen, and cellulose. Ribose and deoxyribose are individual monosaccharide units, not large polymers.

Count the actual carbon atoms in the ring structure rather than recalling the naming convention: both ribose and deoxyribose have a five-membered ring built from five carbon atoms (C1' through C5'). Since 'pent-' simply means five, the carbon count itself determines the classification as pentoses, independent of memorising the trioses/hexoses naming scheme.