The diffusion is a process of transportation through which substances move down towards their concentration gradient means from their higher concentration zone to the lower concentration zone.
The diffusion process is a passive transportation mechanism in which substances move across the plasma membrane down towards their concentration gradient means from their higher concentration zone to the lower concentration zone without using any energy or ATP molecules. As in diffusion, any kind of energy or ATP molecule is not required for transportation that is why it is a passive transport mechanism.
Is diffusion passive? From Wikimedia commons
There are two types of diffusion processes found, such as Simple diffusion and Facilitated diffusion. In a simple diffusion process, substances move from higher to lower concentration zones without using any kind of energy or any kind of external help. In facilitated diffusion substances need some carrier molecules to move according to their concentration gradient.
In the simple diffusion process small, non-polar ions such as gasses, and lipid molecules are majorly transported directly through the cell membrane. In the facilitated diffusion process, large molecules or polar ions such as Glucose, galactose, water, chloride ions, bicarbonate ions, etc are majorly transported through the protein channels within the cell membrane.
How is diffusion passive?
In passive transport mechanisms, any kind of energy or ATP molecules from a cell is not required for the movement of substances across the plasma membrane.
In the diffusion process, substances to be transported move from their higher concentration zone to the lower concentration zone means according to their concentration gradient until the concentration of the two areas becomes equal. During this process, the mechanism does not obtain energy or ATP molecules from the environment that is why the diffusion process is passive in nature.
With the concern to the question, is diffusion passive or not, we can also add that diffusion processes are passive transport mechanisms because instead of using energy from the surrounding for the movement, is driven by Gibbs free energy gradient or chemical gradient.
Is facilitated diffusion a passive transport?
The facilitated diffusion process is a type of diffusion process in which molecules move across the plasma membrane with the help of channel proteins embedded within the cell membrane.
With the concern to the question is facilitated diffusion a passive transport or not? The answer is yes, The facilitated diffusion process is a passive diffusion transport mechanism. It means in this process any kind of energy or ATP molecule is not required for the movement of substances across the plasma membrane. Also, any kind of energy is not required for the activation of the carrier proteins that facilitates the transportation process.
Through facilitated diffusion processes large polar molecules or ions are majorly transported across the plasma membrane with the help of channel proteins. These channel proteins do not require any kind of energy to activate, in presence of some selective molecules such as large molecules, water or polar ions, certain channel proteins get activated and open a channel or pore within the cell membrane so that without coming in contact with the hydrophobic zone of cell membrane the selective molecules diffuses easily.
Facilitated diffusion process from Wikimedia commons
Why is facilitated diffusion a passive transport?
The facilitated diffusion process is a passive transport mechanism which transports water or polar molecules across the plasma membrane.
The facilitated diffusion process is a passive mode of transportation because in this process any kind of energy through cellular ATP hydrolysis is not required for the movement of substances across the plasma membrane. Also, any kind of energy is not necessary for the activation of the carrier proteins that facilitates the transportation process. Without consuming energy when water or selective polar molecules need to be transported across the membrane the channel proteins activate and open a hydrophilic pathway with the cell membrane. So that molecules can be easily diffused through it.
There are several channel proteins which facilitate the process of diffusion and transport water for polar molecules across the cell membrane within a seconds. Some most common protein channels are Aquaporins, calcium ion channels, potassium ions channels, sodium ion channels, etc.
Facilitated diffusion process by Aquaporin from Wikimedia commons
Is simple diffusion passive or active transport?
Simple diffusion is a kind of diffusion process in which molecules move from their higher concentration zone to lower concentration zone according to their concentration gradient without requiring any help from other molecules.
With the concern to the question is simple diffusion process passive or active transport mechanisms? The answer is that a simple diffusion process is typically a passive transport mechanism. In which molecules move from their higher concentration zone to lower concentration zone means according to their concentration gradient without requiring any energy from cellular ATP hydrolysis for the movement of substances.
In this process concentration gradient or chemical, gradient plays the main role which facilitates the molecules to move according to it without requiring any energy or any help from outside molecules of the cellular environment.
Simple diffusion process from Wikimedia commons
Why is simple diffusion passive or active transport?
The simple diffusion process is a typical passive transport mechanism within the cell.
Just like any other passive transport mechanism, the simple diffusion process does not require any energy or ATP molecules from the surrounding environment for the movement of the substances. The concentration gradient or chemical gradient influences the molecules to move from their higher concentration zone to lower concentration zone independently.
Unlike the facilitated diffusion process, simple diffusion does not trigger any channel proteins to open a pore or channel within the cell membrane structure. The best example of a simple diffusion process is the respiration process. In the human body, the oxygen diffuses from the lungs to the blood capillaries and spreads into the blood through the simple diffusion process. Similarly, the carbon dioxide also diffuses from blood capillaries to the lung and alveolus through a simple diffusion process only.
Conclusion
As a whole, we can say that the diffusion process is a very efficient cellular transport mechanism which moves molecules according to their concentration gradient. Here we try to find out the answer to the question: is diffusion passive or not? We also mention some most common facts related to the diffusion process. Hope this article on whether diffusion is passive or not will be helpful to you.
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Hello, I am Piyali Das, pursuing my Post Graduation in Zoology from Calcutta University. I am very passionate on Academic Article writing. My aim is to explain complex things in simple way through my writings for the readers.