LIFE SCIENCE

Detailed explanation-1: -At pH=7, two are negative charged: aspartic acid (Asp, D) and glutamic acid (Glu, E) (acidic side chains), and three are positive charged: lysine (Lys, K), arginine (Arg, R) and histidine (His, H) (basic side chains).

Detailed explanation-2: -Most amino acids are neutral at neutral pH (pH 7) because the carboxylic acid and amine groups balance each other out, however acidic amino acids, like glutamic acid and aspartic acid, have a charge of-1 at pH 7 because their R group loses a proton to the solvent.

Detailed explanation-3: -Substitutions: Glutamate (or Glutamic acid) is a negatively charged, polar amino acid.

Detailed explanation-4: -Two amino acids have acidic side chains at neutral pH. These are aspartic acid or aspartate (Asp) and glutamic acid or glutamate (Glu). Their side chains have carboxylic acid groups whose pKa’s are low enough to lose protons, becoming negatively charged in the process.