Active vs Passive Diffusion
There are different types of transport systems, which help moving substances from one place to another. Basically, there are two mechanisms of transportation; namely active and passive transport. Diffusion is one of the commonest methods found in passive transport. The categorization of those two methods is done based on the criteria of energy consumption. It is very much important to understand those different mechanisms separately and distinguish the ordinary features of them further to set them apart.
What is passive diffusion?
Diffusion is a passive process where no energy is required to proceed. It can be explained as the net movement of a substance from one place to another along a concentration gradient. Concentration gradient is developed by the different concentration areas present in a similar media. The movement is from high concentration to low concentration. Diffusion process can be categorized in to several different types based on the method of transportation. In simple diffusion, solutes are moving down a concentration gradient from high concentration to low concentration. Facilitated diffusion is also a passive transport process, which is engaged with career molecules. In this case, the movements of the given molecules occur through a cell membrane, which is selectively permeable. Some large molecules cannot simply pass though this. Therefore, they need a special support from some other mechanism. Transport proteins, which imbedded in the cell membrane, are modified to do this activity. Movement is done by binding the specific molecule with career protein, and it is still through a concentration gradient. Osmosis is a different type of diffusion where the water molecules are moved across a selectively permeable membrane. Water molecules move through a partially permeable membrane along a gradient in water potential. Filtration is also a type of passive transport system but not diffusion. Feeling the odor of a perfume is resulted due to simple diffusion of chemical compounds through air.
What is active transport?
Active transport is the opposite mechanism of passive transport. It consumes energy to carry on. Movement of material occurs against the concentration gradient, in active transport. Therefore, the net movement will occur from low concentration to high concentration. The active transport systems are categorized into primary and secondary. Those processes use chemical energy (ATP) and electrochemical gradient respectively as the source of energy.
This can occur in human, animal and plant cells. Transportation of mineral ions from soil solution to the root hair cells and intestinal uptakes of sugars are results due to active transport.
What is the difference between active transport and passive diffusion?
• Both are well-known transport methods, which are used by materials, molecules or solvents to distribute. However, they are two different mechanisms of transportation.
• Active transport is an energy consuming process while passive diffusion does not.
• The next important difference between them is based on the relationship between concentration and the net movement. Passive diffusion occurs along a concentration gradient from high concentration to low concentration. At the end, net movement of solute ceases, when the concentrations are similar everywhere. However, in the case of active transport the movement is happening against the concentration gradient from low concentration to high concentration.