Membrenes

• What are the different types of transport across cell membranes?

  1. Passive transport: Requires no energy

  • Diffusion (incl. osmosis)

  
  

  1. Active transport: Requires energy (ATP)
• What characterizes active transport across the cell membrane?

  • Movement of molecules or ions against a concentration gradient
  • Requires energy, usually in the form of ATP from respiration
  • Involves carrier proteins that act as pumps
  • Each carrier protein is specific to a particular molecule or ion
  • It is a highly selective process
• Semipermeable Membrane


  A selective barrier that allows certain substances to pass through while blocking others.
• Cell Membrane


  The outermost layer of a cell, regulating what enters and leaves the cell.
• Phospholipid Bilayer


  A double layer of fatty acid tails (non-polar) and phosphate heads (polar) in the cell membrane.
• Proteins in the Cell Membrane

  Embedded within the bilayer, proteins play crucial roles in transport and function.
• Diffusion


  Movement of molecules from high to low concentration.
• Passive Transport


  <details>Diffusion, osmosis, and facilitated diffusion, no energy required.</details>
• Active Transport


  <details>Requires energy, uses ATP to transport molecules against concentration gradients.</details>
• Primary Active Transport

  <details>Uses ATP to transport molecules against concentration gradients.</details>
• Cell Membrane Permeability


  The extent to which the cell membrane allows certain substances to pass through, influenced by size, charge, and solubility.
• Semipermeable Membrane


  A selective barrier that allows certain substances to pass through while blocking others, crucial for maintaining the cell's internal environment.
• Factors Affecting Permeability


  Temperature, pH, concentration gradients, and enzymes can influence the cell membrane's permeability.
• Passive Transport


  <details>Simple diffusion, osmosis, and facilitated diffusion, no energy required.</details>
• Glucose Transport


  <details>Facilitated diffusion through glucose transporters allows glucose to enter cells.</details>
• Cell Membrane Structure


  Double layer of phospholipids with proteins embedded and cholesterol molecules.
• Phospholipid Bilayer


  A double layer of phospholipids with hydrophilic and hydrophobic regions.
• Proteins in the Cell Membrane

  Embedded in the phospholipid bilayer, proteins play crucial roles in transport and function.
• Cell Membrane Function


  Regulates what enters and leaves the cell, maintains cell volume, and allows nutrients and waste to pass through.
• Osmosis


  Movement of water molecules through the membrane, driven by concentration gradients.
• Diffusion


  Movement of molecules from high to low concentration, no energy required.
• Facilitated Diffusion


  Transport of molecules through protein channels, no energy required.
• Active Transport


  Requires energy, uses ATP to transport molecules against concentration gradients.
• Primary Active Transport


  Uses ATP to transport molecules against concentration gradients.
• Secondary Active Transport

  Uses ATP and facilitated diffusion to transport molecules against concentration gradients.
• Sodium-Potassium Pump

  Primary active transport that pumps sodium ions out of the cell and potassium ions in.
• Glucose Transporter


  Facilitated diffusion through glucose transporters allows glucose to enter cells.
• Na+/Glucose Cotransporter


  Secondary active transport that uses the energy from sodium ions to transport glucose into cells.
• Endocytosis


  The process by which the cell internalizes materials and nutrients by forming vesicles.
• Exocytosis


  The process by which the cell releases materials and waste by fusion of vesicles with the plasma membrane.
• Bulk Flow


  The movement of large volumes of fluid across the cell membrane, often driven by osmotic gradients.
• Osmoregulation


  The process by which the cell regulates its osmotic balance and maintains proper cell volume.
• Cell Membrane Potential


  The electrical potential difference across the cell membrane, generated by the distribution of ions.
• Ion Channels


  Protein channels that allow specific ions to pass through the cell membrane.