Final answer:
In the endocytic pathway, endocytotic vesicles mature into lysosomes, where proton pumps lower pH to around 6.0 to enable digestion of vesicle contents.
Step-by-step explanation:
In the endocytic pathway, endocytotic vesicles fuse with each other to form lysosomes, in which the pH is lowered to around 6.0 by proton pumps.
Once internalized, vesicles shed their coat and join early endosomes, which mature into late endosomes, separating cargo from receptors.
The late endosomes acquire digestive enzymes and become acidic, functional lysosomes with the help of proton pumps, crucial for the breakdown and recycling of the vesicle contents.
This process is essential both for cellular metabolism and for specialized functions such as receptor-mediated endocytosis, adding an important layer of selectivity in the uptake of extracellular substances by the cell.