How do you calculate the average molecular weight of an amino acid residue?

• A. Subtract the mass of a water molecule from the average weight of free amino acids.
• B. Add the mass of a water molecule to the average weight of free amino acids.
• C. Multiply the mass of a water molecule by the average weight of free amino acids.
• D. Divide the mass of a water molecule by the average weight of free amino acids.

Answer: (A)