Mod 5: communication, homeostasis + energy

• What is the structural unit of muscle fibers called?

  Sarcomere
• What protein interacts with actin in muscle contraction?

  Myosin
• What happens to glucose when blood glucose levels are high?

  Glucose is transported into cells by glucose pumps
• How is glucose utilized in the mitochondria?

  It is used to produce ATP
• What effect does ATP binding have on KATP channels?

  ATP binding closes KATP channels
• What occurs after KATP channels close?

  The membrane depolarizes, causing calcium ion channels to open
• What is the result of calcium ions entering the cell?

  It causes vesicles containing insulin to fuse with the cell membrane
• What is the process of creating glucose from amino acids and glycerol called?

  Gluconeogenesis
• What blocks the actin-myosin binding sites?

  Tropomyosin blocks the binding sites
• What is the sliding filament model of muscle contraction?

  1. Action potential depolarizes the sarcoplasmic reticulum (SR)
  2. calcium ion channels on SR open, allowing calcium ions in
  3. calcium ions bind to troponin, changing its shape
  4. Tropomyosin moves away from actin-myosin binding sites
  5. Cross bridges form between actin and myosin heads
  6. Myosin heads flex, pulling actin inwards and shortening sarcomeres
  7. ADP is released from myosin, and ATP binds instead
  8. calcium ions activate ATPase, converting ATP to ADP, returning myosin to its original position
• What is glycogenolysis?

  The conversion of glycogen to glucose
• What is a risk associated with pancreas transplants?

  There is a risk of diabetes
• What is the purpose of immunosuppressants in pancreas transplants?

  To prevent the immune system from rejecting the transplanted organ
• What happens to β-cell metabolism after a pancreas transplant?

  It increases, leading to exhausted capacity for insulin production
• What type of stem cells raises ethical concerns?

  Embryonic stem cells
• What are potential diabetes treatments mentioned?

  1. Insulin injections (risk of denaturation)
  2. Previously sourced from cow/pig, now from genetically modified bacteria

  • Cheaper
  • More ethical
  • Pure (less chance of reaction)
• What happens to insulin if it is not stored properly?

  It will denature
• Why are genetically modified bacteria used for insulin production?

  They are cheaper, more ethical, and produce pure insulin
• How does the process of muscle contraction involve ATP?

  ATP provides energy for myosin head detachment and returns it to its original position
• What is the role of calcium ions in muscle contraction?

  Calcium ions bind to troponin, allowing actin-myosin interactions
• How does the sliding filament model explain muscle contraction?

  It describes how actin and myosin filaments slide past each other to shorten sarcomeres