cell transport methods

• Active transport requires energy from ATP to move substances against their concentration gradients, while passive transport does not require energy as it moves with the concentration gradient.
• Simple diffusion is the movement of molecules across a membrane without any involvement of carrier proteins or other factors.
• Facilitated diffusion involves the use of specific carrier proteins embedded in the plasma membrane that bind to certain molecules and facilitate their passage through the membrane.
• Isotonic solutions have equal concentrations on both sides of the membrane, resulting in no change in volume.
• Hypertonic solutions have higher solute concentrations (lower water potential) than the cell cytoplasm, causing water to leave the cell by osmosis until equilibrium is reached.
• Hypotonic solutions have lower solute concentrations (higher water potential) than the cell cytoplasm, causing water to enter the cell by osmosis until equilibrium is reached.
• Osmosis is the net movement of water molecules across a selectively permeable membrane from an area of low solute concentration (high water potential) to an area of high solute concentration (low water potential).
• Exocytosis is the reverse process of endocytosis, where materials are released outside the cell.
• Endocytosis is the process where cells take up large particles into vesicles formed at the surface of the cell.
• Semi-permeable membranes allow some substances to pass through but prevent others from doing so.
• Facilitated diffusion involves the use of specific carrier proteins embedded in the plasma membrane to facilitate the passage of certain molecules through the membrane.
• Passive transport can be further divided into simple diffusion (no carrier proteins involved) and facilitated diffusion (carrier proteins involved).
• The rate of diffusion depends on the size of the particle, with smaller particles diffusing faster due to their greater kinetic energy.
• co-transport is the movement of 2 substances, using carrier proteins
• active transport process:

  • ATP binds to carrier protein
  • ATP is hydrolysed to ADP and a phosphate group
  • the phosphate group attaches to carrier protein, allowing the protein to change shape, bind to the molecule and transport it across the phospholipid bilayer
• explain the role of carrier proteins in active transport

  1.) Carrier proteins are involved in the movement of substances against their concentration gradient (from low to high concentration).

  2.) They bind specifically to the molecule or ion being transported.

  3.) ATP is required to change the shape of the carrier protein.

  4.)After transport, the carrier protein returns to its original shape.
• • Fick's Law relates the rate of diffusion to the concentration gradient, the diffusion distance and the surface area
  • This relationship can be represented by the following equation, where ∝ means "proportional to"

  rate of diffusion ∝ (surface area x concentration difference) % thickness of membrane