Active transport

• What is active transport?

  Active transport is the process by which molecules move from low to high concentration against a concentration gradient.
• Why is active transport considered an active process?

  Because it requires energy in the form of ATP to move molecules against a concentration gradient.
• What type of proteins are used in active transport?

  Active transport uses carrier proteins and protein channels.
• What are the steps involved in the process of active transport?

  1. Molecule or ion combines with a specific carrier protein on the membrane's outside.
  2. ATP transfers a phosphate group to the carrier protein inside the membrane.
  3. Carrier protein changes shape and transports the molecule or ion across the membrane.
  4. Molecule or ion is released into the cytoplasm.
  5. Phosphate ion is released back to the cytoplasm and recombines with ADP to form ATP.
  6. Carrier protein returns to its original shape.
• What happens to the phosphate ion after it is released from the carrier protein?

  The phosphate ion recombines with ADP to form ATP.
• How do respiratory inhibitors like cyanide affect active transport?

  They stop the rate of active transport by preventing ATP production.
• Why does the absence of oxygen affect active transport?

  Without oxygen, respiration does not occur, leading to no ATP production for active transport.
• What is active transport?

  The movement of substances against a gradient
• What does 'uptake' refer to in the context of concentration gradients?

  A concentration gradient moving from lower to higher
• What does 'down' mean in terms of concentration gradients?

  A concentration gradient moving from higher to lower
• What is another term often used for active transport?

  Active uptake
• Why is ATP important in active transport?

  It provides energy for the transport process
• What is the primary function of carrier proteins in active transport?

  To move molecules across the membrane
• What are the features of active transport?

  • Moves ions/molecules from lower to higher concentration
  • Requires energy from ATP
  • Affected by respiration
  • Occurs through intrinsic carrier proteins
  • Rate limited by carrier protein availability
• What processes involve active transport?

  • Muscle contraction
  • Nerve impulse transmission
  • Reabsorption of glucose in kidneys
  • Mineral uptake in plant root hairs
• How does a carrier protein function in active transport?

  It changes shape to move a molecule across
• What are the steps of active uptake of a molecule or ion?

  1. Molecule combines with carrier protein outside
  2. ATP transfers a phosphate group to the protein
  3. Molecule is released into the cytoplasm
  4. Phosphate ion returns to cytoplasm, forming ATP
  5. Carrier protein returns to original shape
• What happens to the rate of uptake at higher concentration differences?

  It increases and reaches a plateau
• What effect does an inhibitor have on active transport?

  It reduces the rate of uptake
• Why does cyanide reduce active transport?

  It prevents ATP production in mitochondria
• How does increased oxygen availability affect active transport?

  It increases active transport by producing more ATP
• What is the relationship between respiration and active transport?

  Active transport requires energy from respiration
• What are the two types of transport across membranes discussed in the session?

  Active transport and co-transport
• How do molecules move in simple diffusion?

  Down their concentration gradient without a protein
• What is facilitated diffusion?

  Movement down concentration gradient through a protein
• What characterizes active transport?

  Movement against concentration gradient using energy
• What is the energy source required for active transport?

  ATP
• What happens to ATP during active transport?

  It is hydrolyzed into ADP and phosphate
• How does the shape of sodium ions relate to carrier proteins?

  Sodium ions fit into complementary receptor sites
• What happens to the carrier protein after sodium ions are released?

  It returns to its original shape
• What is co-transport in the context of glucose absorption?

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

  High glucose concentration prevents facilitated diffusion
• What role do microvilli play in glucose absorption?

  They increase surface area for absorption
• How does the concentration gradient of sodium ions affect glucose transport?

  Lower sodium concentration allows glucose to enter
• What happens to glucose after it enters the epithelial cell?

  It moves into the blood by facilitated diffusion
• Why does blood not accumulate glucose during absorption?

  Blood flow carries glucose away quickly
• What is the relationship between active transport and co-transport?

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

  1. Sodium ions attach to carrier protein.
  2. ATP hydrolyzes to ADP, releasing phosphate.
  3. Carrier protein changes shape, releasing sodium ions.
  4. Carrier protein returns to original shape.
• How does co-transport of glucose and sodium ions occur in the ileum?

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

  • Active transport moves substances against concentration gradient.
  • Requires energy in the form of ATP.
  • Co-transport involves two molecules moving together.
  • Both processes utilize carrier proteins.