Amino acids contain a carboxyl functional group (-COOH), an amine functional group (Nitrogen atom connected to hydrogen atoms and up to 3 R groups), and a side chain. The alpha carbon is connected to each of these, as well as a hydrogen atom. Amino acids have the ability to donate and accept protons (H+ ions) as the amine group can accept them, and the carboxyl group can donate them. Under neutral conditions, amino acids undergo self ionisation and the carboxyl group donates a proton to the amine group, resulting in a dipolar ion, known as a zwitterion. The zwitterion has separate regions with opposite charges, but overall does not carry a charge.