Diffusion vs Facilitated Diffusion: Difference and Comparison

Facilitated diffusion and diffusion are 2 types of passive transport systems in which substance is transported in the cell with the help of the cell membrane.

Move the molecules with a greater concentration to a lower engagement with the aid of natural entropy until the concentration is equalized.

Key Takeaways

  1. Diffusion is the passive movement of particles from high to low concentration, while facilitated diffusion requires membrane proteins to transport particles.
  2. Facilitated diffusion is selective, allowing only specific molecules to pass through the membrane.
  3. Diffusion is a slower process for larger or charged molecules than facilitated diffusion.

Diffusion vs Facilitated Diffusion

Diffusion is a process in which particles pass between the phospholipids from an area of high concentration to a place of lower concentration. Facilitated diffusion is the process of specialized membrane channels through which particles are diffused because they can’t be diffused directly.

Diffusion vs Facilitated Diffusion

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Diffusion is a type of diffusion in which substances propagate from a greater concentration to a lower concentration without the assistance of other particles.

After the molecules have been uniformly disseminated, molecules on both areas of the cell membrane approach the state of evenness, and hence no sharp movement of the particles can be observed.

Facilitated diffusion is carried out by Using a carrier molecule and concentration gradient. Chemicals are transported through a biological membrane via facilitated diffusion.

Polar molecules and Large ions dissolve in water and are transported through the cell membrane in a controlled and passive way by facilitated diffusion. It diffuses at a quicker rate.

Comparison Table

Parameters of ComparisonDiffusionFacilitated Diffusion
VelocityIt has a faster diffusion rate as compared to normal distribution.It occurs via the phospholipid bilayer
ForcesDiffusion is determined by the concentration gradient which is present across the membrane.The driving force is the pressure difference in the concentration of solute in the membrane.
OccurrenceDiffusion depends on the gradient of concentration in the cell wall and the diffusion rate. It occurs via transmembrane proteins
Diffusion RatesDiffusion moves nonpolar and tiny particles.The kinetics of vector-mediated transport determine the rate of facilitated diffusion.
TransportationDiffusion moves non-polar and tiny particles.It transports polar and large particles.

What is Diffusion?

Solvent density is critical to transport solutes in the cell’s cytoplasm. Diffusion occurs when a chemical moves from a higher percentage of the solution to a low percentage solution area until its concentration is equal throughout a space.

Small nonpolar atoms, like carbon dioxide, ethanol, and oxygen. They pass readily through the cell membrane.

The diffusion rate is affected by molecule size and the slope formed by the concentration gradient. It is one of the body’s methods for regulating chemical concentrations.

As a result, the optimum or optimal concentrations of such compounds in the body may not be obtained immediately. As cytoplasm density increases, the movement of molecules and gases slows, while the converse is true for less dense cytoplasm.

The molecules on each side of the cell membrane attain an equilibrium in which molecules have no net movement after they are equally spread.

The size of the molecules has an impact on the rate of diffusion through a biological membrane. If the molecules are large, they will have more difficulty migrating over the membrane, lowering their diffusion rate.

Lipid-soluble molecules, such as those in the plasma membrane, can quickly move across a lipid layer.

What is Facilitated Diffusion?

Some molecules, such as carbon dioxide and oxygen, can diffuse straight through the plasma membrane, but others require assistance to pass through its hydrophobic core.

In assisted diffusion, molecules migrate across the plasma membrane with membrane proteins such as channels and carriers.

The transfer of ions like potassium and calcium and the propagation of oxygen in the blood through haemoglobin and the propagation of glucose and amino acids in the blood to the cell are all instances of facilitated diffusion.

Because these molecules have a concentration gradient, they can diffuse into (or out of) the cell by travelling with it. However, because they are charged or polar, they cannot traverse the membrane’s phospholipid portion on their own.

The energy barrier associated with the carrier’s conformational shift is more significant than the activation energy of solvent viscosity, which influences diffusion through channel proteins.

Temperature causes carrier transport rates to grow more rapidly. Facilitated transport proteins protect these molecules from the hydrophobic centre of the membrane, allowing them to pass.

Facilitated diffusion is used to carry out critical cellular operations, such as transferring oxygen, nutrients, and ions, which are required to maintain optimum homeostasis in the cell.

Channels and carrier proteins are the two primary types of assisted transport proteins.

Main Differences Between Diffusion and Facilitated Diffusion

  1. Diffusion allows only tiny and nonpolar molecules to pass through the plasma membrane, whereas facilitated diffusion allows big and polar molecules to flow through.
  2. In the case of Diffusion, the Particles propagate in the direction of the concentration gradient, while atoms can travel in both directions — the opposite way and the direction of a concentration gradient.
  3. Diffusion is unaffected by inhibitor molecules, whereas certain inhibitor molecules can prevent aided diffusion.
  4. Diffusion does not require energy from ATP, so it is a non-energy-consuming mode of transportation whereas facilitated diffusion may or may not require energy from ATP.
  5. Diffusion happens straight through the cell membrane whereas facilitated diffusion is facilitated by transmembrane integral proteins, which are specialized facilitator molecules.
  1. https://journals.physiology.org/doi/abs/10.1152/physrev.1990.70.4.1135
  2. https://www.sciencedirect.com/science/article/pii/S0021925818969656

Last Updated : 30 June, 2023

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