Lysosomes, present in nearly all cells, are their key waste disposal route, both for endogenous and exogenous substances (by trafficking of endocytosis vesicles ; deficient trafficking of exogenous cholesterol towards lysosomes leads to Niemann Pick C & D).
Lysosomes owe their efficacy to :
- their excellent out to in permeability (single layer membrane*)
- the low pH at which their enzymes are active, maintained by a H+ pump
- the constant arrival of enzymes produced by the reticulum and "addressed" by the Golgi.
Absence of one of these enzymes, albeit direct consequences of non metabolism of the substrate, leads to lysosomal accumulation of this substrate, puffing up the lysosomes, and severely compromising cell function
Lysosomes : cellular waste disposal
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* Only one other cell organelle has a single layer membrane : the peroxysome. X linked adrenoleukodystrophy appears when it lacks the capacity to metabolize fatty acids