1. Classify insulin as being one of the following
Steroid
- Fatty acid
Protein
Carbohydrate

Protein

Explanation: Insulin is a protein and a peptide hormone with two polypeptide chains joined by two disulfide bonds. Insulin is synthesized in the pancreas as an inactive single-chain precursor, preproinsulin with an amino-terminal signal sequence. Proteolytic removal of the signal sequence and formation of three disulfide bonds produces provision, which is stored in secretory granules in pancreatic cells. Insulin secretion is triggers by high blood glucose level. When elevated blood glucose triggers Insulin secretion, proinsulin is converted into active by specific proteases that cleave two peptide bonds to form the mature insulin molecule. Insulin stimulates glucose uptake by muscle tissue and activates glycogen synthase that catalyzes the synthesis of glycogen and inactivates glycogen phosphoryl which catalyzes the breakdown of glycogen, thereby converting the excess blood glucose to glycogen for storage.

well, i believe that the answer is 2. : 3