Final answer:
Misfolded or mutated proteins are typically degraded and not transported to the Golgi apparatus. These defective proteins are targeted for destruction to prevent diseases caused by protein accumulation, such as proteopathies.
Step-by-step explanation:
Misfolded or mutated proteins that cannot fold properly are degraded and are not transported to the Golgi apparatus. Proteins must fold into their correct three-dimensional shapes to be functional, and misfolding can lead to diseases, termed proteopathies. Diseases such as Alzheimer's and Creutzfeld-Jacob disease feature the accumulation of misfolded proteins, forming plaques that can be toxic to cells. In a healthy cellular process, properly folded and modified proteins are packaged into vesicles at the Golgi's trans face and then either distributed within the cell or released outside the cell.
However, when proteins are misfolded, they often fail to be processed normally within the endomembrane system which includes the endoplasmic reticulum (ER) and the Golgi apparatus. Instead of being transported to the Golgi, these defective proteins are typically targeted for destruction by the cell's quality control mechanisms, such as the proteasome, to prevent their accumulation and the potential harm they could cause.