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