1. Bacteria: These are single-celled organisms that belong to the domain Bacteria. They are prokaryotes, meaning they lack a membrane-bound nucleus and other membrane-bound organelles. Their genetic material (DNA) is located in a region called the nucleoid, which is not enclosed by a membrane.
2. Archaea: These are also single-celled organisms, previously considered bacteria but now recognized as a separate domain. Like bacteria, they are prokaryotes and lack a nucleus. Archaea often live in extreme environments like hot springs or salty lakes.
