A zwitterion (from German "Zwitter" — "hybrid," "hermaphrodite") is a compound with acidic and basic groups in the same molecule. At neutral pH most zwitterions are therefore negatively charged anions and positively charged cations at the same time. Zwitterions usually have a high solubility in water due to their charged groups and a poor solubility in most organic solvents. The 1st-century BC sculpture The Reclining Hermaphrodite, in the Museo Palazzo Massimo Alle Terme in Rome In zoology, a hermaphrodite is an organism of a species whose members possess both male and female sexual organs during their lives. ... It has been suggested that strong acid be merged into this article or section. ... It has been suggested that strong base be merged into this article or section. ... In general, a molecule is the smallest particle of a pure chemical substance that still retains its composition and chemical properties. ... The correct title of this article is pH. The initial letter is capitalized due to technical restrictions. ... An anion is an ion with negative charge. ... A cation is an ion with positive charge. ... A solvent is a liquid that dissolves a solid, liquid, or gaseous solute, resulting in a solution. ...

Zwitterions make good buffer solutions — they resist change to the pH of a solution by selective ionisation. In the presence of acids, zwitterions accept the hydrogen ions, removing them from the solution. In the presence of bases, zwitterions donate hydrogen ions to the solution, again balancing the pH. Buffer solutions are solutions which resist change in hydronium ion concentration (and consequent pH) upon addition of small amounts of acid or base, or upon dilution. ... It has been suggested that strong base be merged into this article or section. ...

Typical examples of zwitterions are:

• Amino acids with their carboxylic acid groups (-COOH) and their basic amino groups (-NH₂).
• Zwitterionic buffer compounds like HEPES, PIPES, CAPS, or MOPS.
• Natural products like the alkaloids psilocin and lysergic acid.

Less common examples of zwitterions are: In chemistry, chemistry is really stupid. ... Structure of a carboxylic acid Carboxylic acids are organic acids characterized by the presence of a carboxyl group, which has the formula -C(=O)-OH, usually written as COOH. In general, the salts and anions of carboxylic acids are called carboxylates. ... Ammonia Amines are organic compounds and a type of functional group that contain nitrogen as the key atom. ... Hepes (4-2-hydroxyethyl-1-piperazineethanesulfonic acid ) is an organic chemical buffer which is widely used in cell culture to maintain physiological pH. Its molecular weight is 238. ... The word pipe can refer to: The basic cylindrical pipe shape a tubular man-made channel, generally round in cross section, in steel or concrete for transporting or guiding a fluid substance see plumbing and pipeline transport used in construction as column, truss element or space frame in mechanical engineering... Caps is the plural of the word cap; see cap (disambiguation). ... Mops can refer to: More than one mop The dog breed also known as Pug This is a disambiguation page: a list of articles associated with the same title. ... An alkaloid is a nitrogenous organic molecule that has a pharmacological effect on humans and animals. ... Psilocin is a mushroom alkaloid and derivative of the psychedelic hallucinogenic drug psilocybin. ... Lysergic acid, also known as D-lysergic acid and (+)-lysergic acid, is a precursor for a wide range of ergoline alkaloids that are produced by the ergot fungus and some plants. ...

• quinonoid zwitterions.

See also: isoelectric point A Quinonoid zwitterion is a special type of zwitterion based on quinone related chemical compounds. ... The isoelectric point sucks (pI) is the pH at which a molecule carries no net electrical charge. ...