Question

What are the functional groups and number of carbons in a ketopentose?

Short answer

A ketopentose has a ketone group and 5 carbons.

Step-by-step solution

Identify the Functional Groups

Ketopentose belongs to the family of carbohydrates. The prefix 'keto' indicates the presence of a ketone (C=O) functional group.

Determine the Number of Carbons

The suffix 'pentose' indicates that the molecule contains five carbon atoms. 'Pent' is derived from the Greek word for five.

Combine the Information

A ketopentose is a sugar molecule that has a ketone functional group and consists of five carbon atoms.

Key concepts

Functional Groups in Carbohydrates

Carbohydrates are essential biomolecules that provide energy and structural components in living organisms. They mainly consist of carbon, hydrogen, and oxygen atoms. One of the primary characteristics of carbohydrates is the presence of functional groups.
Functional groups, such as hydroxyl groups (-OH) and carbonyl groups (C=O), play a crucial role in the chemical properties and reactivity of carbohydrates.
In the context of ketopentoses, the relevant functional group is the ketone group. This is characterized by a carbon atom double-bonded to an oxygen atom (C=O).
The functional groups determine the monosaccharide's classification and its subsequent reactions.

• Hydroxyl group (-OH): Common in all sugars, contributing to their solubility in water.
• Carbonyl group (C=O): Depending on its position within the molecule, this can either be an aldehyde or a ketone. In ketopentoses, it's a ketone.

Ketone Functional Group

The ketone functional group is the defining feature of ketopentoses. This group is situated within the carbon chain and not at the end. In chemical notation, it is represented as C=O.
The presence of a ketone group classifies a sugar as a ketose. For example, in a ketopentose, the ketone group can be found typically on the second carbon atom.
The ketone group plays a significant role in the reactivity and behavior of the carbohydrate.

• Position: Usually, in ketopentoses, the ketone is found on the second carbon.
• Reactivity: The ketone group can engage in reactions such as nucleophilic additions, making ketoses versatile in biochemical pathways.

Carbon Count in Sugars

Sugars, or carbohydrates, are often classified based on the number of carbon atoms they contain. This is denoted by specific prefixes:

• Triose (3 carbons)
• Tetrose (4 carbons)
• Pentose (5 carbons)
• Hexose (6 carbons)

In the case of ketopentose, 'pentose' specifies that the sugar molecule contains five carbon atoms.
This classification is important as it affects the sugar's structure and function. Five-carbon sugars, like ribose and deoxyribose, are vital components of nucleic acids like RNA and DNA.
Understanding the carbon count helps in determining the specific properties and utilities of the sugar in biological processes.

• Important Pentoses: Ribose and Deoxyribose are crucial for genetic material.
• Structural Significance: The carbon count influences the sugar ring formation and its biological role.