Are ribosomes constantly fixed to any structure?

Ribosomes are not constantly fixed to any structure; they can exist as free ribosomes in the cytoplasm or be bound to the endoplasmic reticulum, forming rough ER. Free ribosomes typically synthesize proteins that function within the cytosol, while those bound to the rough ER are primarily involved in synthesizing proteins destined for secretion or for use in membranes. The association with the rough ER is dynamic, depending on the cell's needs.