What is the proper classification of the amino acids involved in the mnemonic "HRDKE"?

• A. Neutral AAʻs
• B. Basic AAʻs
• C. Electric AAʻs
• D. Polar AAʻs

Answer: (C)

The correct classification of the amino acids involved in the mnemonic "HRDKE" is based on the specific properties of each amino acid represented by the letters.

The mnemonic "HRDKE" corresponds to the amino acids Histidine (H), Arginine (R), Aspartic acid (D), Lysine (K), and Glutamic acid (E). By examining these amino acids, we find that they all possess side chains that carry a positive or negative charge under physiological conditions, which classifies them as charged amino acids.

Histidine and Arginine are basic amino acids, as they can accept protons and carry a positive charge, particularly at physiological pH. Aspartic acid and Glutamic acid are acidic and carry a negative charge in physiological conditions. Therefore, the correct classification must encompass the properties of these amino acids relating to their charge rather than treating them as strictly neutral, polar, or potentially misrepresented as "electric."

The term "electric amino acids" is not a standard classification in biochemistry, while polar amino acids typically refer to those with polar but uncharged side chains. Thus, the marks of charge and pH interactions are essential in recognizing the classification of amino acids represented in the mnemonic "HRD