Question

Study the image given below and select the correct statement.

• A. The protein contains 15 amino acids
• B. The left end of the chain is C-terminal
• C. The right end of the chain is N-terminal
• D. The left end of the chain is N-terminal

Answer 1

The correct option is D The left end of the chain is N-terminal

The protein chain shown in the figure has a total of 12 amino acids (represented as small spheres connected by a peptide bond) in its primary structure. The left end represents the first amino acid and the right end represents the last amino acid. The first amino acid is also called as the N-terminal amino acid due to the presence of free amino $\left(N{H}_3^{+}\right)$ group. The last amino acid is called C-terminal amino acid because of the presence of a carboxyl $\left(CO{O}^{-}\right)$ group.