Transport methods

• What is diffusion?

  Diffusion is the net movement of molecules from high to low concentration down their concentration gradient.
• Why is diffusion considered a passive process?

  Because it does not require energy in the form of ATP.
• What drives diffusion?

  Diffusion is driven by the natural kinetic energy of molecules.
• In what environments does diffusion occur?

  Diffusion occurs in both liquid and gaseous environments.
• What are the characteristics of diffusion?

  • Passive process: No energy (ATP) required.
  • Concentration gradient: Molecules move from high to low concentration.
  • Equilibrium: Continues until molecules are evenly distributed.
• What is simple diffusion?

  Simple diffusion occurs when small, non-polar molecules pass through the phospholipid bilayer directly.
• Give examples of molecules that undergo simple diffusion.

  Examples include gases like oxygen (O₂) and carbon dioxide (CO₂).
• What is facilitated diffusion?

  Facilitated diffusion is a passive transport process for larger or polar molecules that require transport proteins to cross the membrane.
• What are the two main types of membrane proteins involved in facilitated diffusion?

  Channel proteins and carrier proteins.
• How do channel proteins function in facilitated diffusion?

  Channel proteins form water-filled channels that allow specific ions or small molecules to pass through the membrane.
• What is the role of aquaporins?

  Aquaporins are specialized channels that allow water molecules to pass through the membrane more efficiently.
• Describe the mechanism of facilitated diffusion.

  It involves binding, conformational change, transport, and re-equilibrium of the molecule across the membrane.
• What are the characteristics of facilitated diffusion?

  • Specificity: Transport proteins are specific to particular molecules.
  • Saturation: Can become saturated if all transport proteins are occupied.
  • No energy requirement: Moves molecules down their concentration gradient without ATP.
• What is an example of facilitated diffusion involving glucose?

  Glucose is transported into cells by GLUT (glucose transporter) proteins.
• How do ion channels function in facilitated diffusion?

  Ion channels allow specific ions to pass through the membrane, such as Na⁺, K⁺, Ca²⁺, or Cl⁻.
• What is the importance of aquaporins in cells?

  Aquaporins allow water to move more rapidly across the membrane, especially in cells with high water permeability.
• What are the roles of diffusion and facilitated diffusion in cells?

  • Obtain nutrients: Uptake of glucose, amino acids, and oxygen.
  • Remove waste products: Elimination of carbon dioxide.
  • Maintain homeostasis: Regulation of ion movement.
  • Signal reception: Transport of signaling molecules for cell communication.
• What is the clinical relevance of diffusion in cystic fibrosis?

  The CFTR channel defect affects chloride ion transport, leading to thick mucus buildup.
• How does insulin resistance relate to facilitated diffusion?

  In type 2 diabetes, the GLUT4 transporter is less responsive to insulin, reducing glucose uptake.
• Why is understanding drug transport important in drug development?

  It helps design drugs that can be transported into specific cells via facilitated diffusion.
• Summarize the key points about diffusion and facilitated diffusion.

  • Diffusion is passive movement from high to low concentration, driven by kinetic energy.
  • Simple diffusion involves small, non-polar molecules; facilitated diffusion involves larger, polar molecules using transport proteins.
  • Both processes do not require energy (ATP) and are crucial for cellular functions.
• What is the definition of diffusion?

  Passive movement of particles from high to low concentration
• Why is diffusion considered a passive process?

  It requires no energy, relying on kinetic energy
• What happens during diffusion until equilibrium is reached?

  Concentration becomes equal across the system
• What is the effect of a steeper concentration gradient on diffusion?

  Increases the rate of diffusion
• How does temperature affect the rate of diffusion?

  Higher temperatures increase kinetic energy, speeding diffusion
• Why does larger surface area increase the rate of diffusion?

  More space allows more particles to diffuse
• How does distance affect the rate of diffusion?

  Shorter distances allow faster diffusion
• Which type of molecules diffuse faster, smaller or larger ones?

  Smaller molecules diffuse faster
• In which medium does diffusion occur faster, gases or liquids?

  Diffusion is faster in gases
• What is an example of diffusion in biology?

  Gas exchange in the lungs
• What is facilitated diffusion?

  Passive transport using transport proteins
• What are channel proteins?

  Proteins that form pathways for specific ions
• How do voltage-gated ion channels function?

  Open or close in response to membrane potential
• What are aquaporins specialized for?

  Water transport across membranes
• What do carrier proteins do in facilitated diffusion?

  Bind and change shape to transport molecules
• What is an example of facilitated diffusion in biology?

  Uptake of glucose via GLUT transporters
• What is the definition of osmosis?

  Diffusion of water across a selectively permeable membrane
• What is the direction of water movement in osmosis?

  From high water potential to low water potential
• What is a hypotonic solution?

  Higher water potential compared to another solution