Final answer:
Materials brought into a cell through endocytosis are enclosed in vesicles that can fuse with other cellular components for further processing, such as in the immune response where antigens are presented by MHC class II molecules.
Step-by-step explanation:
When a cell brings material inside, it is often through a process known as endocytosis. There are different variations of endocytosis, such as phagocytosis, pinocytosis, and receptor-mediated endocytosis. During endocytosis, the cell's plasma membrane invaginates, forming a pocket around the target particle. This pocket then pinches off to become a vesicle that carries substances into the cell. Particularly, in receptor-mediated endocytosis, receptors on the cell's surface bind to external substances triggering the formation of clathrin-coated pits, which then internalize the substance as vesicles.
Once inside, these vesicles can fuse with other vesicles, such as those from the Golgi complex, and eventually the particles or antigens contained may be associated with major histocompatibility complex (MHC) class II molecules. This is crucial for the immune response, as professional antigen-presenting cells utilize this mechanism to present extracellular antigens to the immune system, potentially stimulating a T cell response to fight off infections like viruses, bacteria, and other pathogens.
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