Structures of Amino Acids Amino acid zwitterions Are internal salts Have large dipole moments Are soluble in water but are insoluble in hydrocarbons Are crystalline substances with relatively high melting points Are amphiprotic Can react as acids Reaction takes place in an aqueous base solution Loses a proton to form an anion Can react as bases Reaction takes place in an aqueous acid solution Accepts a proton to yield a cation 0 In acid solution +H20 In base solution H20Amino acid zwitterions ▪ Are internal salts ▪ Have large dipole moments ▪ Are soluble in water but are insoluble in hydrocarbons ▪ Are crystalline substances with relatively high melting points ▪ Are amphiprotic ▪ Can react as acids ▪ Reaction takes place in an aqueous base solution ▪ Loses a proton to form an anion ▪ Can react as bases ▪ Reaction takes place in an aqueous acid solution ▪ Accepts a proton to yield a cation Structures of Amino Acids