Cell Transport Mechanisms

Sure, here’s a structured list of points for the topic “Cell Transport Mechanisms”.

Cell Membranes

  • Made of a phospholipid bilayer, which is semi-permeable, controlling what enters and leaves the cell.
  • The bilayer is embedded with various proteins including carrier proteins and channel proteins, which aid active and passive transport respectively.

Types of Transport Mechanisms

  • Passive Transport: Includes diffusion, osmosis, and facilitated diffusion. These do not require energy (ATP) as substances move down a concentration gradient from high to low concentration.
  • Active Transport: Transport against the concentration gradient (low to high concentration). This process requires energy in the form of ATP.


  • Involves the movement of substances from an area of high concentration to an area of low concentration until equilibrium is reached.
  • Factors affecting the rate of diffusion include temperature, concentration gradient, and surface area.


  • A specific type of diffusion, where water molecules move across a semi-permeable membrane from a region of high water potential (low solute concentration) to low water potential (high solute concentration).

Facilitated diffusion

  • Involves the use of membrane proteins to help the movement of substances which cannot directly pass through the phospholipid bilayer.

Active Transport

  • The use of energy to transport substances across the cell membrane against the concentration gradient.
  • Two types of active transport are primary active transport, which uses ATP directly, and secondary active transport, which uses an electrochemical gradient.

Endocytosis and Exocytosis

  • Endocytosis is the process where the cell membrane engulfs materials to bring them into the cell. This is a type of active transport.
  • Exocytosis is when materials are expelled from the cell by being enveloped in a cell membrane which then fuses with the outer cell membrane. Another form of active transport.

Remember to recall and understand how these mechanisms work, as they underpin many biological processes at the cellular level.