Both Assertion and Reason are true but Reason is not correct explanation of Assertion. A Zwitter ion, also called an inner salt, is a molecule that contains an equal number of positively and negatively charged functional groups. In aqueous solutions, amino acids mostly exist as H3N+−CHR−COO−(Zwitter ion). L-proline is the only one out of the twenty DNA-encoded amino acids which has a secondary amino group alpha to the carboxyl group. It is an essential component of collagen and is important for proper functioning of joints and tendons.