Very large substances can enter the cell by endocytosis. During this process, the plasma membrane surrounds the substance and then fused with the surface of the cell and opens into the cell to remove the substance. In the opposite manner, large substances can leave the cell by exocytosis. At this stage, the substance will be inside a vesicle. This will fuse with the membrane on the inside and release the content allowing the substance out of the cell. Ribosomes, composed of proteins and rRNA, are often found attached to the Endoplasmic reticulum, but may also occur freely in the cytoplasm. Groups of free ribosomes are called Poly ribosomes. Ribosomes are the site of protein synthesis. A protein produced on a free ribosome has a different function than a protein produced at an attached ribosome.
Explanation:
Endocytosis is a process in which cell ingests large particle via cell membrane and bring it to the cell.
Exocytosis is a process in which vesicles fuse with the plasma membrane and eject the substance out of the cell.
Both endocytosis and exocytosis requires energy in the form of ATP.
Ribosome can be either free or attached on rough endoplasmic reticulum.
Membrane-bound ribosomes protein on Endoplasmic reticulum forms protein that is transported to the other cells while free ribosomes produce protein that is to be used in the cell itself.
