Final answer:
True, proteins to be secreted are synthesized at ribosomes on the rough endoplasmic reticulum and then undergo modifications before being secreted.
Step-by-step explanation:
The statement that proteins to be secreted outside of a eukaryotic cell are formed at ribosomes on the surface of the rough endoplasmic reticulum (RER) is true. Protein synthesis begins similarly for all proteins with the formation of an initiation complex, followed by elongation cycles. However, the secretory proteins, lysosomal proteins, peroxisomal proteins, and others meant for organelles are completed within the cisternae of the RER. This is because these kinds of proteins are not destined to remain within the cytosol.
As the proteins are synthesized by the ribosomes bound to the RER, they are inserted into the lumen of the RER. There, they may undergo modifications before being packaged into transport vesicles. These vesicles then fuse with the Golgi apparatus, where further modifications may occur, before the proteins are sent to their final destinations, such as outside the cell.