Question

What is facilitated diffusion and active transport ?

Answer 1

Active Transport vs Facilitated Diffusion

Facilitated diffusion is the process of transport of substances across a cell membrane with the help of carrier or channel proteins. There is another type of movement referred to as active transport where molecules get transported across the plasma membrane taking help of carrier proteins but energy is expended in the process that differentiates it from simple facilitated diffusion. There are similarities in the two processes that confuse many and they cannot differentiate between the two. This article will highlight the two processes making it simple for the students to differentiate between the two processes of active transport and facilitated diffusion.
There are two ways through which substances can enter or leave a cell and these are known as passive and active ways. Among passive ways are simple diffusion, facilitated diffusion and osmosis, whereas active ways involve movement of atoms and molecules. We all know about diffusion and how it allows movement of solution from places of higher concentration to places of lower concentration across a selectively permeable membrane that does not allow passage of large molecules. Facilitated diffusion is a type of diffusion that is also called passive transport. In a cell, polar molecules and charged ions cannot diffuse easily across cell membrane and only small non polar molecules such as oxygen are allowed to pass through plasma membrane. This is where carrier proteins come in handy, behaving like cross membrane channels allowing polar molecules to move across cell membrane. The proteins also regulate the flow of ions and polar molecules closing and opening at intervals. These proteins have their own shape and allow only a single molecule or closely related molecules to pass through membrane.
The entire process of facilitated diffusion is passive and requires no energy from the cell. On the other hand, active transport is a kind of transport of substances across a membrane that demands energy as it is against its concentration gradient that is from lower to higher concentration. The energy required for active transport comes from ATP that is generated through a process called respiration. This kind of movement is for accumulation of molecules that a cell needs such as glucose, amino acids and ions. Uptake of glucose in human beings in the intestine and minerals (ions) into root hair cells of plants are good examples of active transport.
Difference Between Active Transport and Facilitated Diffusion
• Facilitated diffusion, which is a kind of passive transport, requires no energy for the molecules to move into or out of the cell
• Active transport requires energy from the system for the movement of molecules across cell membrane
• Large molecules are helped in their movement in facilitated diffusion by carrier proteins
• The energy for the transport of molecules in active transport comes from ATP
• Osmosis and diffusion are examples of passive transport
• Uptake of glucose in the intestine in human beings is an example of active transport
• Active transport takes place against concentration gradient of the substance.