What are the two main types of cells?

The distinction between the two main types of cells lies in their cellular structure and organization. Eukaryotic cells are characterized by having a true nucleus enclosed within a membrane, along with other membrane-bound organelles such as the endoplasmic reticulum and mitochondria. This type of cell is found in organisms that are more complex, including animals, plants, fungi, and protists.

In contrast, prokaryotic cells do not have a nucleus or membrane-bound organelles. Their genetic material is typically a single circular strand of DNA located in a region called the nucleoid. Prokaryotic cells are generally simpler and smaller than eukaryotic cells and are primarily represented by bacteria and archaea.

This classification into eukaryotic and prokaryotic cells provides a fundamental framework for understanding the diversity of life at the cellular level, as each type of cell plays a unique role in the ecology and physiology of living organisms. The other answer options focus on specific categories or types of cells that are subsets of these broader categories, rather than addressing the primary division in cell biology.