Cell | Definition, Types, Functions, Diagram, Division, Theory,
2025年1月6日 · A cell, in biology, is the basic membrane-bound unit that contains the fundamental molecules of life and of which all living things are composed. A single cell may be a complete organism in itself, such as a bacterium, or it may acquire a specialized function, becoming a building block of a multicellular organism.
Cell theory | Definition, History, Importance, Scientists, First ...
2025年1月14日 · Cell theory, fundamental scientific theory of biology according to which cells are held to be the basic units of all living tissues. First proposed by German scientists Theodor Schwann and Matthias Jakob Schleiden in 1838, the theory that all plants and animals are made up of cells marked a great
Biology | Definition, History, Concepts, Branches, & Facts | Britannica
2024年11月24日 · Cell biology is the study of cells—the fundamental units of structure and function in living organisms. Cells were first observed in the 17th century, when the compound microscope was invented.
Structure and types of cells | Britannica - Encyclopedia Britannica
cell, In biology, the basic unit of which all living things are composed; the smallest structural unit of living matter that is able to function independently. A single cell can be a complete organism in itself, as in bacteria and protozoans .
Cell - Molecules, Structure, Biology | Britannica
2025年1月6日 · Cell - Molecules, Structure, Biology: Cells are largely composed of compounds that contain carbon. The study of how carbon atoms interact with other atoms in molecular compounds forms the basis of the field of organic chemistry and plays a large role in understanding the basic functions of cells.
Stem cell | Definition, Types, Uses, Research, & Facts | Britannica
2025年1月16日 · A stem cell is an undifferentiated cell that can divide to produce some offspring cells that continue as stem cells and some cells that are destined to differentiate (become specialized).
Membrane | Definition, Structure, & Functions | Britannica
membrane, in biology, the thin layer that forms the outer boundary of a living cell or of an internal cell compartment. The outer boundary is the plasma membrane, and the compartments enclosed by internal membranes are called organelles.
Cell - Structure, Organelles, Metabolism | Britannica
2025年1月6日 · Cell - Structure, Organelles, Metabolism: Like the cell membrane, membranes of some organelles contain transport proteins, or permeases, that allow chemical communication between organelles.
Cell membrane | Definition, Function, & Structure | Britannica
2025年1月15日 · Cell membrane, thin membrane that surrounds every living cell. The cell membrane functions as a barrier, keeping cell constituents in and unwanted substances out, and as a gate, allowing transport into the cell of essential nutrients and movement from the cell of waste products.
Biology - Cell Discovery, Microscopy, Histology | Britannica
2024年11月24日 · Biology - Cell Discovery, Microscopy, Histology: Of the five microscopists, Robert Hooke was perhaps the most intellectually preeminent. As curator of instruments at the Royal Society of London, he was in touch with all new scientific developments and exhibited interest in such disparate subjects as flying and the construction of clocks.