How are facilitated diffusion and active transport similar? How are they different?

Facilitated diffusion and active transport are both mechanisms that cells use to move substances across their membranes, but they have distinct similarities and differences.

Similarities

1. Transport Proteins: Both facilitated diffusion and active transport involve the use of transport proteins embedded in the cell membrane to move substances across the membrane.
2. Specificity: Both processes are specific, meaning that the transport proteins are selective for particular substances or types of molecules.

Differences

1. Energy Requirement:

   • Facilitated Diffusion: Does not require energy (ATP) because it relies on the concentration gradient, moving substances from an area of higher concentration to an area of lower concentration.
   • Active Transport: Requires energy (usually in the form of ATP) because it moves substances against their concentration gradient, from an area of lower concentration to an area of higher concentration.

2. Direction of Movement:

   • Facilitated Diffusion: Moves substances down their concentration gradient.
   • Active Transport: Moves substances against their concentration gradient.

3. Examples:

   • Facilitated Diffusion: Glucose transport into cells via GLUT transporters.
   • Active Transport: Sodium-potassium pump (Na+/K+ pump) which maintains the electrochemical gradient in cells.

Final Answer

Facilitated diffusion and active transport both use transport proteins and are specific to certain molecules. However, facilitated diffusion does not require energy and moves substances down their concentration gradient, while active transport requires energy to move substances against their concentration gradient.