A major difference in the structure of proteins, fats, and carbohydrates is that only proteins always contain (A) carbon (B) hydrogen (C) oxygen (D) sodium (E) nitrogen
Nitrogen. Remember this saying: CHO CHO CHON CHONP. Carbohydrates are CHO, fats are CHO, proteins are CHON, and nucleic acid is CHONP. Between carbs, fats, and proteins, proteins are CHON, the only one with nitrogen.
