Question

What is the molecular weight of insulin?
A. 15000 Da
B. 5000 Da
C. 4000 Da
D. 5800 Da

Answer 1

Hint: Insulin is a peptide hormone. This hormone is secreted by the Beta – cells of the pancreatic islets. Pancreas is a gland located behind Stomach.

Complete Answer:
Insulin: The word insulin is derived from latin word ‘insula’ which means island.
- Insulin is considered to be the main anabolic hormone of the body.
- The hormone insulin regulates the metabolism of carbohydrates, fats and proteins by promoting the absorption of glucose.
- The glucose absorbed from the blood gets stored into the liver, fat and skeletal muscle cells.
- In these tissues absorbed glucose is converted into either glycogen by glycogenesis or fats (triglycerides) via lipogenesis or in case of liver into both glycogen and fats.

Structure of insulin: The insulin is a first peptide hormone which was found to be quite large.
- A single protein of human insulin is composed of 51 amino acids and has a molecular mass of 5800 Da.
- Insulin is a dimer and a combination of two peptide chains named as A-chain and B-chain.
- Both the chains are linked together by disulfide bonds.
- A-chain is composed of 21 amino acids while B-chain is composed of 30 amino acids.
The human insulin is also composed of C-chain but it is only present in proinsulin not in the active form of insulin.
- Proinsulin gets converted into active insulin through the action of cellular endopeptidase called Prohormone Convertase (PC1 and PC2) as well as exopeptidase Carboxypeptidase E.

Disease caused by the variation in concentration of insulin:
- Type 1 diabetes: Type 1 diabetes is a type of autoimmune disease. It results due to the deficiency of insulin. In this type of disease the immune system attacks and destroys the insulin producing Beta-cells in the pancreas so the body is unable to produce insulin and blood glucose level increases.
- Type 2 diabetes: In type 2 diabetes , the body of a person produces inadequate amounts of insulin but in this case the body is unable to use it effectively.

Hence, option D is the correct answer for this question.

Note: Pancreas is an endocrine gland. Endocrine glands are the gland that produces hormones and releases the hormones directly into the blood or circulatory system. These glands are also called the ductless glands.