Dec 10, 2025 · What is a cell? A cell is a mass of cytoplasm that is bound externally by a cell membrane. Usually microscopic in size, cells are the smallest structural units of living matter …

Every organism, or living thing, is made up of structures called cells. The cell is the smallest unit with the basic properties of life. Some tiny organisms, such as bacteria…

Encyclopædia Britannica, Inc. The smallest unit of living matter that can exist by itself is the cell. Some organisms, such as bacteria, consist of only a single cell. Others, such as large animals …

Jan 2, 2026 · cell theory, fundamental scientific theory of biology according to which cells are held to be the basic units of all living tissues.

Jan 6, 2026 · A cell is a mass of cytoplasm that is bound externally by a cell membrane. Usually microscopic in size, cells are the smallest structural units of living matter and compose all …

Dec 5, 2025 · A plant cell is the basic unit of all plants. Plant cells, like animal cells, are eukaryotic, meaning they have a membrane-bound nucleus and organelles. Their …

Cell differentiation is a crucial part of development in multicellular organisms, since it results in cells with unique characteristics—such as muscle cells, neurons, or red blood cells —and …

5 days ago · White blood cell, cellular component of blood that helps defend the body against infection. White blood cells defend against infection and disease by ingesting foreign materials …

Jan 7, 2026 · There are two major types of stem cells: embryonic stem cells and adult stem cells, which are also called tissue stem cells.

Jan 2, 2026 · Eukaryote, any cell or organism that possesses a clearly defined nucleus. The eukaryotic cell has a nuclear membrane that surrounds the nucleus, in which the well-defined …