Which of the following statements about prokaryotic cells is correct?

Prokaryotic cells are characterized by their simpler structure compared to eukaryotic cells. One of the key features of prokaryotic cells is that they do not have a defined nucleus. Instead, their genetic material, which consists of a single circular chromosome, is located in a region called the nucleoid. This contrasts with eukaryotic cells, which contain a membrane-bound nucleus that encloses their genetic material.

Moreover, prokaryotic cells lack membrane-bound organelles, which is another distinction from eukaryotic cells that typically have structures like mitochondria, endoplasmic reticulum, and Golgi apparatus. Prokaryotes are generally smaller than eukaryotic cells, and they perform cellular respiration through processes that take place in the cell membrane rather than in mitochondria. All these characteristics highlight why the statement that prokaryotic cells lack a defined nucleus is accurate.