AP BIOLOGY

Detailed explanation-1: -Insulin plays a central role in the regulation of human metabolism. The hormone is a 51-residue anabolic protein that is secreted by the -cells in the Islets of Langerhans.

Detailed explanation-2: -Insulin is a hormone that is essential for regulating energy storage and glucose metabolism in the body. Insulin in liver, muscle, and fat tissues stimulates the cell to take up glucose from blood and store it as glycogen in liver and muscle. Failure of insulin control causes diabetes mellitus (DM).

Detailed explanation-3: -Insulin is a small globular protein containing two chains, A (21 residues) and B (30 residues) (Fig. 2.1A). Stored in the cell as a Zn2+-stabilized hexamer, the hormone dissociates in the bloodstream to function as a Zn2+-free monomer (Fig. 2.1B).

Detailed explanation-4: -Insulin is a protein composed of two chains, an A chain (with 21 amino acids) and a B chain (with 30 amino acids), which are linked together by sulfur atoms. Insulin is derived from a 74-amino-acid prohormone molecule called proinsulin.

Detailed explanation-5: -any of a class of substances secreted into the bloodstream that regulate processes in distant target organs and tissues and that consist of a long-chain polymer of amino acids. Examples are parathyroid hormone, prolactin, growth hormone, and insulin.