transport across membrane

• What are the two types of transport across membranes discussed in the session?

  Active transport and co-transport
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• What is the first type of transport mentioned that does not involve a protein?

  Simple diffusion
• What is the second type of transport that involves a protein and moves down the concentration gradient?

  Facilitated diffusion
• What is the third type of transport that requires energy?

  Active transport
• What is the definition of active transport?

  Movement from low to high concentration
• What energy source is required for active transport?

  ATP
• What type of proteins are involved in active transport?

  Carrier proteins
• What happens to ATP during active transport?

  It is hydrolyzed into ADP
• What does the hydrolysis of ATP cause in the carrier protein?

  Change in shape of the protein
• What is the role of sodium ions in active transport?

  They attach to the carrier protein
• What happens to the carrier protein after sodium ions are released?

  It returns to its original shape
• What is co-transport specifically used for in the ileum?

  Absorption of glucose with sodium ions
• Why is active transport necessary for glucose absorption in the ileum?

  High concentration of glucose in epithelial cells
• What happens to sodium ions during the absorption of glucose?

  They move from the lumen into the epithelial cell
• What is the role of microvilli in the epithelial cells?

  Increase surface area for absorption
• How does the concentration gradient of glucose affect its movement?

  Glucose moves down its concentration gradient
• What maintains the concentration gradient of glucose in the blood?

  Constant flow of blood
• What is the relationship between active transport and co-transport?

  Co-transport is a type of active transport
• What are the steps involved in the co-transport of glucose and sodium ions in the ileum?

  1. Sodium ions are actively transported into the blood.
  2. Sodium ions diffuse from the lumen into the epithelial cell.
  3. Glucose attaches to the co-transporter protein with sodium.
  4. Both sodium and glucose are transported into the epithelial cell.
  5. Glucose moves into the blood by facilitated diffusion.
• What are the key features of active transport and co-transport?

  • Active transport requires ATP.
  • Co-transport involves two molecules.
  • Both processes use carrier proteins.
  • Active transport moves substances against their gradient.
• What is the significance of carrier proteins in active transport?

  • They facilitate the movement of substances.
  • They change shape to transport molecules.
  • They are specific to certain molecules.
  • They require energy from ATP.
• What is the role of ATP in active transport?

  • Provides energy for transport.
  • Hydrolyzed to ADP and inorganic phosphate.
  • Causes conformational changes in carrier proteins.
  • Essential for moving substances against concentration gradients.
• How do microvilli enhance absorption in the ileum?

  • Increase surface area for absorption.
  • Allow more co-transporter proteins to be present.
  • Facilitate efficient nutrient uptake.
  • Improve contact with digested food.