To determine: The functional groups that give a molecule a positive charge and a negative charge.
Introduction: Functional groups are a part of organic molecules that determine their properties and chemical reactions. They 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.
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.
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.
Refer Table 1-2, “Common Functional Groups and Linkages in Biochemistry”, in the textbook. 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.