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From these conclusions about plants and animals, two of the three tenets of cell theory were postulated. 1. All living organisms are composed of one or more cells 2. The cell is the most basic unit of life. Schleiden's theory of free cell formation through crystallization was refuted in the 1850s by Robert Remak, Rudolf Virchow, and Albert ...
A uniform resource locator (URL), colloquially known as an address on the Web, [1] is a reference to a resource that specifies its location on a computer network and a mechanism for retrieving it. A URL is a specific type of Uniform Resource Identifier (URI), [ 2 ] [ 3 ] although many people use the two terms interchangeably.
The book is credited with the first description of what would later be called Schwann cell, a type of glial cell. [3] The description of the cells was evident from passages such as: [3] Some, however, appear to remain for a longer period; occasionally, although rarely, a cell-nucleui is here and there seen upon the side of a nerve (the white ...
Image from his textbook The Cell in Development and Inheritance, second edition, 1900. Edmund Beecher Wilson (October 19, 1856 – March 3, 1939) [2] was a pioneering American zoologist and geneticist. He wrote one of the most influential textbooks in modern biology, The Cell. [3] [4] He discovered the chromosomal XY sex-determination system in ...
A prokaryotic cell has three regions: Enclosing the cell is the cell envelope, generally consisting of a plasma membrane covered by a cell wall which, for some bacteria, may be further covered by a third layer called a capsule.
Light micrograph of a moss's leaf cells at 400X magnification. The following outline is provided as an overview of and topical guide to cell biology: . Cell biology – A branch of biology that includes study of cells regarding their physiological properties, structure, and function; the organelles they contain; interactions with their environment; and their life cycle, division, and death.
In biology, cell signaling (cell signalling in British English) is the process by which a cell interacts with itself, other cells, and the environment. Cell signaling is a fundamental property of all cellular life in prokaryotes and eukaryotes. Typically, the signaling process involves three components: the signal, the receptor, and the effector.
In evolutionary biology, the term cellularization (cellularisation) has been used in theories to explain the evolution of cells, for instance in the pre-cell theory, [1] [2] [3] dealing with the evolution of the first cells on this planet, and in the syncytial theory [4] attempting to explain the origin of Metazoa from unicellular organisms.