Final answer:
During endocytosis, the membrane pocket enclosing a particle breaks loose and forms an intracellular vesicle. After the vesicle's contents are processed, the vesicular membrane reincorporates into the plasma membrane.
Step-by-step explanation:
During endocytosis, a pocket forms in a cell's plasma membrane which then engulfs a target particle. This process involves a protein called clathrin that stabilizes the section of the membrane. As the membrane encloses the particle, the pocket pinches off from the membrane forming an intracellular vesicle. Once inside, clathrin disengages, and the vesicle fuses with a lysosome. The contents of the vesicle are broken down, and nutrients are extracted. Subsequently, the vesicle, now called an endosome, fuses back with the plasma membrane, thus reincorporating its membrane materials and releasing any undigested contents out of the cell.This cycle ensures that the plasma membrane does not simply increase in size over time and is crucial for maintaining cellular homeostasis.