Similarity Between Simple Diffusion and Facilitated Diffusion

Simple Diffusion and Facilitated Diffusion are two of the four types of Passive Transport. 

What is Passive Transport?

Passive transport is a type of molecular transport where the substances move from a region of higher concentration to a region of lower concentration. 

Since the movement is down the concentration gradient, this movement does not require energy. 

Passive transport follows Fick’s first law and the second law of thermodynamics to facilitate the movement of molecules or ions. This explains the increase in the entropy of the overall system which relinquishes the requirement of cellular energy.

It causes the uniform distribution of molecules or ions and results in achieving dynamic equilibrium.

The rate of passive transport depends on several factors such as temperature, solvent density, the mass of molecules or ions diffusing, and extent of the concentration gradient. 

Passive transport has four main kinds which are Simple diffusion, Facilitated diffusion, Osmosis and Filtration.

What is Simple Diffusion?

Simple diffusion is a type of passive transport as molecules move down the concentration gradient without the requirement of cellular energy. 

It is the transport of molecules through a selectively permeable biological membrane without the aid of membrane proteins.

It allows the cell to maintain homeostasis inside the cell.   

The rate of Simple Diffusion is generally slower as this process is not relying on the binding capacity of the transport proteins. 

It involves the transport of small nonpolar molecules such as oxygen and carbon dioxide which can easily diffuse across the cell membrane.  

What is Facilitated Diffusion?

Facilitated Diffusion is also a type of passive transport. 

It is a process in which only selected molecules moves across the semi-permeable membrane in the presence of specific transmembrane carrier proteins. 

It allows the cell to maintain homeostasis inside the cell.   

These carrier proteins which are involved in Facilitated diffusion are gated transmembrane channels and they do not translocate internally. The molecule is taken in from one side of the gated channel and released into the cell without the use of ATP.  

Facilitated diffusion plays a vital role in several metabolic processes.

Facilitated diffusion is especially used for the transport of large polar molecules and charged ions. When these ions dissolve in water they are unable to diffuse freely across the cell membranes since the cell membrane has hydrophobic tails consisting of phospholipids. Therefore, to facilitate the movement of such substances, a transport protein is used.

The rate of facilitated diffusion is generally faster because of the function of carrier protein. However, the rate depends on the temperature, permeability of the cell membrane, characteristics of the membrane lipids, types of membrane proteins involved, and membrane protein inhibitors. 

Facilitated diffusion involves the transport of polar molecules (such as glucose and amino acids), large ions (such as sodium ions and chloride ions), and large nonpolar molecules (such as retinol) which are unable to diffuse across the cell membrane on their own.  

What are the similarities between Simple Diffusion and Facilitated Diffusion?

Similarities in terms of type and concentration gradient:

Both are a type of passive transport, where molecules move down the concentration gradient. 

Similarities in terms of thermodynamics: 

Both processes follow Fick’s first law and the second law of thermodynamics. 

Similarities in terms of Energy requirements:

Since the movement is down the concentration gradient due to which the entropy of the overall system increases, both the prosses do not require cell energy (for example from ATP or GTP) for the movement of the particles. 

Similarities in terms of membrane:

In both processes, substances pass through a semipermeable cell membrane. 

Similarities in terms of purpose:

Purpose of both Simple Diffusion and Facilitated Diffusion is to maintain homeostasis inside the cell.   

Summary

• Simple Diffusion and Facilitated Diffusion are among the four types of Passive transport.  

• Transport of substances in both simple and facilitated diffusion occurs across a semi-permeable cell membrane and is down the concentration gradient. 

• Simple Diffusion occurs without the involvement of transport proteins. 

• Facilitated Diffusion requires the involvement of transport proteins. 

• Both Simple Diffusion and Facilitated Diffusion do not require any cell energy for example from ATP or GTP. 

• Both Simple Diffusion and Facilitated Diffusion allows the cell to maintain homeostasis inside the cell.   

• Simple Diffusion transports small nonpolar molecules.

• Facilitated Diffusion can transport polar molecules, large ions, and large nonpolar molecules.

• The rate of Simple Diffusion is slower than the rate of Facilitated Diffusion. 

FAQs

What are the similarities between simple diffusion and active transport?

Both Simple diffusion and active transport facilitate cellular transport across a biological membrane. Both allow the cell to maintain homeostasis inside the cell.   

What do three types of diffusion have in common?

All three types of diffusion are forms of passive transport hence substances move down the concentration gradient and do not require energy to facilitate the transport. 

What is the similarity between osmosis and facilitated diffusion?

Osmosis and facilitated diffusion are types of passive transport hence substances move down the concentration gradient and do not require energy to facilitate the transport. Both allow the cell to maintain homeostasis inside the cell.   

What are the similarities and differences between facilitated diffusion and active transport by a protein pump?

Protein pumps are transmembrane carrier proteins that transport ions against the concentration gradient.

In both facilitated diffusion and active transport, molecules move across the semi-permeable membrane in the presence ofspecific transmembrane carrier proteins. 

Facilitated diffusion occurs down the concentration gradient and therefore does not require cellular energy, however active transport occurs up the concentration gradient and therefore requires cellular energy. 

What are the similarities and differences between diffusion, osmosis, and active transport?

• All these three processes of diffusion, osmosis, and active transport facilitate cellular transport across a biological membrane and allow the cell to maintain homeostasis inside the cell. 

• Both Osmosis and Diffusion are types of passive transport hence substances move down the concentration gradient and do not require energy to facilitate the transport.

• Osmosis is the transport of water molecules, whereas diffusion is the transport of other molecules or ions through a semi-permeable membrane. 

• Active transport is not a type of passive transport as the substances move against the concentration gradient and requires energy to do so. 

How are passive transport and facilitated diffusion alike?

One of the types of passive transport is Facilitated diffusion as the transport of substances takes place from a region of high concentration to a region of lower concentration.