Which option explains why this amino acid can act as both an acid and a base?
The option that explains why an amino acid can act as both an acid and a base is because it contains both acidic and basic functional groups. Amino acids have an amino group (-NH2) which can donate a proton (H+) and act as a base, and they also have a carboxyl group (-COOH) which can release a proton and act as an acid. This dual nature allows amino acids to undergo both acid-base reactions, making them amphoteric.
The ability of an amino acid to act as both an acid and a base is due to the presence of two functional groups: the carboxyl group (-COOH) and the amino group (-NH₂).
When an amino acid acts as an acid, it donates a proton (H⁺) from its carboxyl group, resulting in the formation of a negatively charged carboxylate ion (-COO⁻). This process is known as deprotonation.
On the other hand, when an amino acid acts as a base, it accepts a proton (H⁺) onto its amino group, resulting in the formation of a positively charged ammonium ion (-NH₃⁺). This process is called protonation.
The ability of an amino acid to act as either an acid or a base depends on the environmental conditions, such as the pH of the solution and the presence of other molecules that can donate or accept protons. Under different conditions, an amino acid can exist in different forms: as a zwitterion (with both a positive and a negative charge) or as an ion with either a positive or a negative charge.