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Insulin quiz #1

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  • What is the structure of insulin and how is it activated from its precursor form?
    Insulin is a small peptide hormone with 51 amino acids, consisting of two polypeptide chains linked by disulfide bonds. It is initially secreted as proinsulin, an inactive zymogen, by pancreatic beta cells. Proinsulin is activated through proteolysis, which removes a connecting segment and results in the active, two-chain insulin molecule.
  • Describe the three primary biological effects of insulin in the human body.
    The three primary biological effects of insulin are: (1) decreasing blood glucose concentration, (2) stimulating cell growth, and (3) increasing lipid synthesis.
  • How does insulin decrease blood glucose concentration after a meal?
    Insulin decreases blood glucose by increasing the expression of the GLUT4 glucose transporter, which imports glucose into cells, and by promoting glycogen synthesis, which converts free glucose inside cells into glycogen, thereby lowering intracellular glucose and facilitating further glucose uptake from the blood.
  • Through what type of receptor does insulin exert its effects, and what is a key signaling pathway involved?
    Insulin exerts its effects through the insulin receptor, which is a receptor tyrosine kinase (RTK). The RTK signaling pathway is key to mediating insulin's actions, including lowering blood glucose and stimulating cell growth.
  • How does insulin stimulate cell growth, and does this use the same pathway as its effect on blood glucose?
    Insulin stimulates cell growth by acting as a growth factor and regulating gene expression via a specific RTK biosignaling pathway. This pathway is different from the one used to lower blood glucose concentration.
  • What is the structure of insulin and how is it activated from its precursor form?
    Insulin is a small peptide hormone with 51 amino acids, consisting of two polypeptide chains linked by disulfide bonds. It is initially secreted as proinsulin, an inactive zymogen, and is activated by proteolytic cleavage that removes a connecting segment, resulting in the active two-chain insulin molecule.
  • Describe the three primary biological effects of insulin in the human body.
    The three primary biological effects of insulin are decreasing blood glucose concentration, stimulating cell growth, and increasing lipid synthesis.
  • How does insulin decrease blood glucose concentration after a meal?
    Insulin increases the expression of the GLUT4 glucose transporter to import glucose into cells and promotes glycogen synthesis, converting free glucose inside cells into glycogen, which lowers intracellular glucose and facilitates further glucose uptake from the blood.
  • Through what type of receptor does insulin exert its effects, and what is a key signaling pathway involved?
    Insulin exerts its effects through the insulin receptor, which is a receptor tyrosine kinase (RTK). The RTK signaling pathway is key to mediating insulin's actions, including lowering blood glucose and stimulating cell growth.
  • How does insulin stimulate cell growth, and does this use the same pathway as its effect on blood glucose?
    Insulin stimulates cell growth by acting as a growth factor and regulating gene expression via a specific RTK biosignaling pathway. This pathway is different from the one used to lower blood glucose concentration.