Ch.13 Carbohydrates

Timberlake - Chemistry: An Introduction to General, Organic, and Biological Chemistry 13th Edition

Timberlake13th EditionChemistry: An Introduction to General, Organic, and Biological ChemistryISBN: 9780134421353Not the one you use?Change textbook

Timberlake 13th Edition

Ch.13 Carbohydrates

Problem 7

Chapter 13, Problem 7

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

Verified step by step guidance

Understand the term 'ketopentose': A ketopentose is a monosaccharide (simple sugar) that contains a ketone functional group and five carbon atoms.

Identify the functional group: The ketone group is characterized by a carbon atom double-bonded to an oxygen atom (C=O). In a ketopentose, this group is located within the carbon chain, not at the end.

Determine the number of carbons: The prefix 'pent-' in 'ketopentose' indicates that the molecule contains five carbon atoms.

Visualize the structure: A ketopentose has a backbone of five carbon atoms, with one of the internal carbons forming the ketone group (C=O). The remaining carbons are typically bonded to hydroxyl groups (-OH) or hydrogen atoms.

Summarize: The functional group in a ketopentose is a ketone (C=O), and the molecule contains a total of five carbon atoms.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Functional Groups

Functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. In carbohydrates, common functional groups include hydroxyl (-OH) and carbonyl (C=O) groups. Understanding these groups is essential for identifying the properties and reactivity of sugars, including ketopentoses.

Ketopentose

A ketopentose is a type of sugar that contains five carbon atoms and has a ketone functional group. The general formula for pentoses is C5H10O5, and they can exist in linear or cyclic forms. The presence of the ketone group distinguishes ketopentoses from aldopentoses, which have an aldehyde group instead.

Number of Carbons

The number of carbons in a carbohydrate is crucial for classifying the type of sugar. In the case of ketopentoses, there are five carbon atoms, which influences their structure and function in biological systems. This classification helps in understanding their role in metabolism and their structural variations.