Final answer:
The process by which a cell degrades its own components, including defective mitochondria, is known as autophagy and involves lysosomal breakdown.
Step-by-step explanation:
The mechanism used for degrading obsolete parts of a cell, such as a defective mitochondrion, is called autophagy. Autophagy is a process by which a cell degrades its own components through the action of lysosomes.
These organelles fuse with the cellular structures in need of removal, like damaged mitochondria, and use their hydrolytic enzymes to break them down.
This cellular 'cleanup' is essential for cellular health and homeostasis. It is distinctly different from apoptosis, which is programmed cell death of the whole cell, and phagocytosis, which is the engulfing of external particles or cells.
Autophagy is like an internal recycling program, ensuring that cellular components are efficiently reused and that defective parts do not accumulate, thus maintaining cell function and viability.