Which feature distinguishes prokaryotic cells from eukaryotic cells?

The distinguishing feature between prokaryotic cells and eukaryotic cells is the presence of a nucleus. Prokaryotic cells, such as bacteria and archaea, do not have a membrane-bound nucleus or other organelles; instead, their genetic material is located in a nucleoid region, which is not enclosed. In contrast, eukaryotic cells, which include plant, animal, and fungal cells, have a true nucleus that houses their DNA within a double membrane. This structural difference is a key factor in the classification of cells and influences various cellular functions and processes.

While ribosomes are present in both prokaryotic and eukaryotic cells, it is the nucleus that serves as a primary defining characteristic. Prokaryotic cells are generally smaller, but size alone does not differentiate between the two types, as eukaryotic cells can vary widely in size. Additionally, both types of cells can perform photosynthesis, particularly in certain prokaryotic species, so this feature cannot be used to categorize cells into prokaryotic and eukaryotic.