Final answer:
Prokaryotic cells are unicellular organisms without a nucleus or membrane-bound organelles, and include bacteria and archaea.
Step-by-step explanation:
Cells with no nucleus or organelles with membranes are known as prokaryotes. Prokaryotic cells are simple, single-celled organisms that lack a nucleus and membrane-bound structures such as mitochondria, chloroplasts, and endoplasmic reticulum. In contrast to eukaryotic cells, which contain a nucleus and organelles, prokaryotic cells house their DNA in the cytoplasm and have ribosomes for protein synthesis but without a nucleus or other highly organized membrane-bound organelles. Examples of these organisms include bacteria and archaea, with bacteria comprising shapes like cocci (spherical), bacilli (rod-shaped), and spirilli (spiral-shaped).