Which component is NOT typically found in prokaryotic cells?

Prokaryotic cells are characterized by their simple structure, lacking a membrane-bound nucleus. Instead, their genetic material, which is DNA, is typically found in a region called the nucleoid, that is not enclosed within a membrane. This absence of a nucleus is a fundamental distinction between prokaryotic cells and eukaryotic cells, which do have a defined nucleus that houses their DNA.

The other components listed are integral to prokaryotic cells. They contain DNA, which is essential for carrying genetic information. Prokaryotic cells are also surrounded by a cell membrane that regulates the movement of substances in and out of the cell. Additionally, ribosomes are present in prokaryotic cells and play a crucial role in protein synthesis by translating messenger RNA (mRNA) into proteins. Thus, the presence of DNA, ribosomes, and a membrane, alongside the absence of a nucleus, are all indicative of the characteristics defining prokaryotic cells.