Final answer:
Ribosomes are cell organelles found either floating freely in the cytoplasm or attached to the rough endoplasmic reticulum, where they are involved in protein synthesis.
Step-by-step explanation:
Ribosomes can be found in a cell in two main locations. They can either be floating freely in the cytoplasm or they may be attached to the endoplasmic reticulum (ER). When ribosomes are attached to the ER, it is referred to as the rough ER, due to its bumpy appearance under a microscope, which is a result of the presence of the ribosomes on its surface. Additionally, ribosomes are present in the mitochondria and chloroplasts, where they resemble the ribosomes found in prokaryotic cells more than the ones in the nuclear cells.
Ribosomes are important for protein synthesis in cells and can appear as either clusters or single tiny dots when observed under an electron microscope. The ones found on the rough ER are specifically involved in the synthesis of proteins that are either to be integrated into the cell membrane or exported out of the cell.