Question

How does diffusion differ from endocytosis and exocytosis?

Answer 1

Hint: Diffusion is a process used for the movement of substances in and out of a cell depending upon their concentration gradients. Endocytosis and Exocytosis are the vesicle-mediated transport of the cell that transports large molecules.

Complete answer:
The net movement of particles or substances from a region of its higher concentration to a region of its lower concentration without the expenditure of ATP or energy is known as Diffusion. The diffusion of substance completely depends on the concentration gradient between the two areas. The movement of substances in diffusion occurs from a region of higher concentration to a lower concentration. This is a downhill process and thus occurs passively. It occurs mainly in liquids and gases as they have molecules that undergo random movement.

Endocytosis is a cellular process that involves the intake of large molecules or substances from the outside to the inside of the cell. The large molecules are engulfed by the membrane of the cell and are taken in through vesicles. The membrane of the cell folds to form a cavity around the substance. The cavity is filled with extracellular fluid. After the invagination of the substance, the folding of the membrane folds back to trap the substance inside it, thus forming a vesicle. The vesicle detaches from the membrane and goes inside the cell for further processing. It is used for modulating cellular responses, cell signaling, uptake of nutrients, etc.

Exocytosis is a cellular process that involves the removal of large molecules or substances from the inside to the outside of the cell. The large molecules are enclosed within a vesicle, which fuses with the plasma membrane, and releases the substances outside the cell. The vesicles are transported from the inside to the cell membrane. It then fuses with the membrane and releases its content after the fusion. The substances are expelled out from the cell. It is responsible for removing the waste and toxic substances from the cell.
The substances that cannot cross the plasma membrane due to their size or polarity are transported by- the endocytosis/exocytosis processes.

Diffusion differs from endocytosis/ exocytosis as-
1)Diffusion is a passive process, while endocytosis/ exocytosis is an active process.
2)The process of diffusion is not controlled by the cell, while endocytosis/ exocytosis is fully controlled by the cell.
3)Diffusion is not an energy-dependent process- but endocytosis/ exocytosis are energy-dependent processes.
4)The movement of substances occurs directly through the cell membrane in diffusion. In endocytosis/ exocytosis, the movement of substances occurs through a vesicle.
5)Lipids and proteins are required in the process of endocytosis/ exocytosis to form vesicles. 6)Diffusion does not require any specific protein molecules.
7)The movement in endocytosis/ exocytosis occurs due to a pressure gradient. In diffusion, the movement of molecules occurs due to a concentration gradient.
8)In diffusion, only solutes travel from a region of higher concentration to a region of lower concentration. In endocytosis/ exocytosis, the entire solution is transferred.
9)The endocytosis/ exocytosis is a receptor-mediated process, while diffusion is not.

Note: Exocytosis and endocytosis are both types of bulk transport. They require the expenditure of energy and carrier proteins for the movement of ions and molecules. It is a process by which proteins with a signal- transfer to and fro from cellular compartments. Endocytosis and exocytosis are responsible for maintaining the homeostasis of a cell, so the number of ions/molecules leaving the cell will be equal to the number of molecules/ions entering the cell.