Kaplan Nursing Entrance Practice Exam 2026 – The All-in-One Guide to Exam Success!

Eukaryotic cells are defined by the presence of a nucleus, which is a membrane-bound organelle that contains the cell's genetic material. This structural characteristic distinguishes them from prokaryotic cells, which do not have a nucleus and instead have their genetic material located in a region called the nucleoid. Eukaryotic cells make up a diverse range of organisms, including animals, plants, fungi, and protists.

In contrast, prokaryotic cells, such as bacterial cells, lack a defined nucleus and do not have membrane-bound organelles. This fundamental difference is one of the key characteristics used to classify cells into prokaryotic and eukaryotic groups. Red blood cells are a specific type of eukaryotic cell but are unique because they typically lose their nucleus as they mature, allowing for more space to carry hemoglobin and, thereby, oxygen. Hence, while red blood cells are eukaryotic, their mature form does not contain a nucleus.

Understanding the distinctions among these cell types is essential in the field of biology, as it underpins much of the complexity of cellular functions and the diversity of life.