Question

What is a prosthetic group of a protein?
(a) Amino acid
(b) Peptide chain
(c) Polypeptide chain
(d) Non-protein component

Answer 1

Hint: These are metal ions or a chemical compound which are used by the enzymes for their activities; they are also essential for various metabolic activities.

Complete answer:
A prosthetic group of a protein is a non-protein component. It is a part of the structure of the hetero proteins or conjugated proteins, being covalently linked to the apoprotein. The prosthetic group is required for the protein's biological activity and is a component of a conjugated protein.
The vitamin, sugar, RNA, phosphate, or lipid are organic prosthetic groups whereas the iron metal is an inorganic prosthetic group. These groups are bound tightly to proteins that are attached through a covalent bond.
An apoprotein is a protein without its prosthetic group whereas a holoprotein is a protein that remains combined with its prosthetic group.
The prosthetic groups are also said to be a set of cofactors. The loosely bound metal ions and coenzymes are called cofactors but they are not called the prosthetic group.
In the catalytic mechanism, the prosthetic group is involved and these are also required for various activities of enzymes.
In hemoglobin, a heme group is a prosthetic group. Vitamin derivatives such as thiamine pyrophosphate, pyridoxal-phosphate, and biotin are examples of some organic prosthetic groups.
The transition metal ion such as iron, zinc, copper, and molybdenum are examples of inorganic prosthetic groups.

Hence, the correct answer is option (d).

Note:
The prosthetic group is a part of the structure of the hetero proteins or conjugated proteins and is a non-amino acid or non-protein component.
The prosthetic group plays an important role in the catalysis of enzymes.
The prosthetic group for the sugar and lipid moieties in glycoproteins and lipoproteins or RNA in ribosomes have structural properties.