"Nucleated" refers to a structure or cell that contains a nucleus, which is a membrane-bound organelle that houses genetic material. In biology, nucleated cells are typically found in organisms like animals and plants, where the nucleus plays a crucial role in regulating cellular functions and heredity. In contrast, some cells, such as red blood cells in mammals, are anucleated, meaning they lack a nucleus. This adaptation allows for more space to carry hemoglobin, the protein responsible for oxygen transport. Understanding the difference between nucleated and anucleated cells is essential in fields like cell biology and medicine.