Here's why:

* Prokaryotic cells: These cells lack a nucleus and other membrane-bound organelles. Ribosomes are essential for protein synthesis, which is a fundamental process for all living organisms.

* Eukaryotic cells: These cells have a nucleus and other membrane-bound organelles. Ribosomes are found both in the cytoplasm and attached to the endoplasmic reticulum (ER) in eukaryotic cells.

Therefore, ribosomes are a universal component of all cells, regardless of whether they are prokaryotic or eukaryotic.