Which of the following is a non-protein component of a conjugated protein?

• A. Prosthetic group
• B. Amino acid sequence
• C. Peptide bond
• D. Polysaccharide chain

Answer: (A)

Conjugated proteins combine a protein part with a non-protein component that is tightly bound and essential for the protein’s activity. That non-protein piece is called a prosthetic group. It’s the part that gives the protein its specific function, such as the heme group in hemoglobin or cytochromes, which are not made of amino acids.

The amino acid sequence and the peptide bonds are intrinsic to the protein portion—they define the polypeptide chain itself, not a separate non-protein moiety. A polysaccharide chain could be attached in some glycoconjugates, but the standard term used for the non-protein, tightly bound component that enables activity is prosthetic group.