Explain zwitterion formation.

In the subtopic Amino acids and proteins (A-level only), this AQA A-Level Chemistry 7405 learning objective focuses on explain zwitterion formation. It belongs to Amino acids, proteins and DNA (A-level only), so revision should stay anchored to this exact subtopic rather than drifting into a generic GCSE-level chemistry summary. Approved keywords to use include zwitterion. Amino acid. means an amino acid is an organic compound that contains both an amine group (-NH2) and a carboxylic acid group (-COOH) Avoid the mistake of students think a zwitterion is a neutral molecule with no internal charges; instead, explain that a zwitterion contains both a positively charged ammonium group (–NH₃⁺) and a negatively charged carboxylate group (–COO⁻) on the same amino‑acid, giving a net zero charge but internal charges that must be considered when describing its formation For exam answers, when amino acids are in solution, they can exist as zwitterions, which are dipolar ions. To explain this, remember that the amino group (-NH2) can accept a proton (H+) while the carboxylic acid group (-COOH) can donate a proton. This results in a zwitterion with both a positive and a negative charge, but an overall neutral charge