Which description best fits insulin?

Which description best fits insulin?

• A. A lipid hormone
• B. A nucleic acid
• C. A carbohydrate
• D. A protein hormone and a signaling molecule

Answer: (D)

Insulin is a protein hormone and a signaling molecule. It’s a peptide produced by pancreatic beta cells, made of amino acids, not a lipid, nucleic acid, or carbohydrate. As a signaling molecule, it travels in the bloodstream and binds to insulin receptors on target cells, triggering a cascade that promotes glucose uptake (notably by muscle and fat cells) and storage as glycogen or fat. This combination of being a peptide-based hormone and acting as a signaling messenger is what best describes insulin, rather than anything lipid, nucleic acid, or carbohydrate.

Insulin is a protein hormone and a signaling molecule. It’s a peptide produced by pancreatic beta cells, made of amino acids, not a lipid, nucleic acid, or carbohydrate. As a signaling molecule, it travels in the bloodstream and binds to insulin receptors on target cells, triggering a cascade that promotes glucose uptake (notably by muscle and fat cells) and storage as glycogen or fat. This combination of being a peptide-based hormone and acting as a signaling messenger is what best describes insulin, rather than anything lipid, nucleic acid, or carbohydrate.