Chapter 1, Problem 1E

Summary Introduction

To determine: The functional groups that give a molecule a positive charge and a negative charge.

Introduction: Functional groups refer to specific group of atoms or bonds in a compound and have characteristic properties. They impart charge to the hydrocarbon chain; for example, alcohols, carboxylic acids, amines, ethers, and ketones.

Answer to Problem 1E

Correct answer: An amino group or imino group gives a positive charge to a molecule, and a carboxylate or phosphoryl group gives a negative charge to a molecule.

Explanation of Solution

Functional groups are the reactive regions of molecules that are functionalized with these specific groups. The common functional groups are alcohols (-OH), carbonyls (C=O), carboxylic acids (-COOH), amines (-NH₂), and esters (-COOR). They are classified on the basis of their charge and polarity.

The functional groups associated with biomolecules that impart a positive charge on them include amino group (-NH₃⁺) and imino group. They can accept H⁺ and impart a positive charge.

The functional groups that impart a negative charge to the biomolecules are carboxylate group, alcohol group, phosphoanhydride group, and phosphodiester linkages. They release H⁺ and impart a negative charge. These functional groups are present in most biomolecules such as carbohydrates, proteins, and nucleic acids.