Final answer:
The name of the complex responsible for degrading proteins that are old, damaged, or misfolded is the proteasome, which includes the 20S proteasome complex and the 19S proteasome cap.
Step-by-step explanation:
The complex that degrades proteins that have reached the end of their lifespan or are damaged or misfolded is called the proteasome. The mechanism for identifying these proteins involves a molecule called ubiquitin, which tags the protein for degradation. This targeted protein is then delivered to the proteasome, a large complex of polypeptides which includes the 20S proteasome complex and the 19S proteasome cap complex. The proteasome digests the protein into short peptide fragments, which are then released and broken down into free amino acids.