Here's why:

* Cell Wall: Bacteria have a rigid cell wall made of peptidoglycan, which gives them their shape and protects them from the environment.

* No Nucleus: Unlike plant and animal cells, bacteria are prokaryotic, meaning they lack a membrane-bound nucleus. Their genetic material (DNA) is located in a region called the nucleoid, but it's not enclosed by a separate membrane.

Let me know if you'd like more information about bacterial cells!