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cell, in biology, the basic membrane-bound unit that contains the fundamental molecules of life and of which all living things are composed. A single cell is often a complete organism in itself, such as a bacterium or yeast. Other cells acquire specialized functions as they mature.
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.
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 .
Stem cell, 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). Stem cells are an ongoing source of the differentiated cells that make up the tissues and organs of animals and plants.
Red blood cell, cellular component of blood that carries oxygen from the lungs to the tissues and gives vertebrates’ blood its characteristic color. The mature human red blood cell is small, round, and biconcave. Red blood cells also carry carbon dioxide, a waste product, to the lungs, where it is excreted.
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.
white blood cell, a cellular component of the blood that lacks hemoglobin, has a nucleus, is capable of motility, and defends the body against infection and disease by ingesting foreign materials and cellular debris, by destroying infectious agents and cancer cells, or by producing antibodies.
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 and yeast, consist of only one cell. Large plants and animals have many billions of cells.
nucleus, in biology, a specialized structure occurring in most cells (except bacteria and blue-green algae) and separated from the rest of the cell by a double layer, the nuclear membrane.
Cell cycle, the ordered sequence of events that occur in a cell in preparation for cell division. The cell cycle is a four-stage process in which the cell increases in size, copies its DNA, prepares to divide, and divides. Learn more about the cell cycle and the proteins that regulate its progression.