Correct Option
Insulin is a peptide hormone. It is composed of 51 amino acids arranged in two polypeptide chains (A and B) linked by disulfide bridges. Secreted by the beta cells of the Islets of Langerhans in the pancreas, insulin plays a crucial role in regulating blood glucose levels by promoting cellular glucose uptake and its storage as glycogen in liver and muscle tissues.
Incorrect Options
Option 1 (glycolipid): Glycolipids are complex lipids containing a carbohydrate moiety. They are primarily found in cell membranes, involved in cell recognition and adhesion, and are not hormones.
Option 2 (fatty acid): Fatty acids are carboxylic acids with long aliphatic chains, serving as building blocks for lipids and energy storage. They do not function as hormones.
Option 4 (sterol): Sterols are a type of lipid characterized by a steroid nucleus. While some hormones, such as steroid hormones, are derived from sterols, insulin is not a sterol.