Why is passive transport important?
Passive transport involves the movement of solutes based on the concentration of substances inside and outside the cell. It requires low energy for the movement of the substances passively. Passive transport is mainly responsible for taking in small substances and for osmoregulation. The protein interaction in the cell due to pumps, gates and channels tend to control the passive transport. When substances are moved from their low concentration to high, the carrier proteins are helpful in this matter. The process requires energy and it is known as active transport. Passive transport is movement of substances across the cell membrane which does not require energy. The types of passive transport are diffusion, facilitated diffusion, filtration and osmosis.
Passive transport of substances takes place from their high to low concentrations and hence they do not require energy expenditure for this process. Another name for this passive process is called as diffusion. The permeability of cell membrane is responsible for passive transport which depends on the lipids and proteins in the membrane. Passive transport of substances continues until the concentration gradient is removed in diffusion process. Passive transport also is accompanied by a carrier protein down the concentration gradient which is known as facilitated movement. Here, even if the pore size is small and the carrier protein will help in the process of movement.
Movement of solute molecules through the cell membrane due to hydrostatic pressure is classified as filtration. Solutes of a particular size are only allowed in this process. Osmosis is the movement of water or solvent molecules across the selectively permeable membrane. Osmosis also involves transfer of solvent molecules from high to low concentrations like that of passive movement. The mechanism of passive transport aids in making use of electrochemical gradient. The protein receptors that form the gates in the channels inside the plasma membrane help in transferring the solute molecules. The electrochemical gradient maintenance is important as ions and charged molecules have to take care of the electrical potential across the membrane.
Movement of glucose through the membrane into the cell exemplifies the facilitated diffusion. The membrane pores of Bowman’s capsule in the kidneys and liver cells are examples for filtration.