Classify each amino acid by the chemical properties of its side chain (R group) at pH 7 . Select the amino acid that fits best in each category. Each amino acid will be selected only once. Which amino acid has a positively charged R group

The amino acid that has a positively charged R group are LYSINE and ARGININE.

Explanation:

AMINO ACIDS are the basic structural units of proteins. Each amino acid contains an amino group ( -NH2) and a carboxyl group (-COOH) in its molecule. The carbon atom of amino acid to which the functional groups are attached is know as the alpha-carbon. In neutral solution, amino acids are mainly in the form of dipolar ions. Amino acids can be prepared through hydrolysis of protein by boiling with dilute hydrochloric acid.

Amino acids can be classified according to the chemical properties of its side chain (R group) at pH 7, these include:

--> Amino acids with POSITIVELY CHARGED R group

--> Amino acids with negatively charged R group

--> Amino acids with neutral polar R group

--> Amino acids with nonpolar aliphatic R group.

Amino acids with POSITIVELY CHARGED R group are those amino acids that has side chains which contain nitrogen and resemble ammonia, which is a base. Their pKa's are high enough that they tend to bind protons, gaining a positive charge in the process. Example include LYSINE and ARGININE.