Biology · BIOMOLECULES

Consider the following statements regarding amino acids: (A) Amino acids are organic compounds containing an amino group and an acidic group on the same \( \alpha \)-carbon. (B) The R group in serine is a methyl group, while in alanine it is a hydroxy methyl group. (C) Tyrosine, phenylalanine, and tryptophan are aromatic amino acids. (D) In solutions of different pH, the structure of an amino acid changes, and at a particular pH it exists as a zwitterion with zero net charge. Which of the above statements are correct?

1. (A), (C) and (D) only
2. (B), (C) and (D) only
3. (B) and (D) only
4. (A), (B) and (C) only