Which type of cell is characterized by the absence of a nucleus?

The type of cell characterized by the absence of a nucleus is the prokaryotic cell. Prokaryotic cells, such as bacteria and archaea, lack a membrane-bound nucleus and instead have their genetic material located in a region called the nucleoid. This structural distinction sets prokaryotes apart from eukaryotic cells, which do have a defined nucleus where their DNA is enclosed.

Prokaryotic cells also tend to be smaller and simpler in structure than eukaryotic cells, and they usually reproduce asexually through binary fission. Understanding this difference is crucial in biology, as it relates to how life is organized at the cellular level and has implications for taxonomy, genetics, and evolution.