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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.
Small cell lung cancer is often treated as a systematic disease due to its tendency for early dissemination, [4] thus, instead of the traditional TNM staging system, the Veterans' Administration Lung Study Group (VALSG) introduced a simplified 2-stage system in the 1950s to divide small cell lung cancer into limited stage and extensive stage. [7]
The proportion of the cells counted applies if not all inner squares within a set square are counted (i.e., if only 4 out of the 20 in a corner square are counted, then this term will equal 0.2). When counting large squares with a volume of 100 nanoliter (nL), a multiplication by 10000 leads to the desired cell count per milliliter.
On 2021, Stephen Quake guessed that the upper limit of the number of human cell types would be around 6000, based on a reasoning that "if biologists had discovered only 5% of cell types in the human body, then the upper limit of cell types to discover is somewhere around 6000 (i.e., 300/0.05)." [10] Other different efforts have used different ...
Mitotic cell division enables sexually reproducing organisms to develop from the one-celled zygote, which itself is produced by fusion of two gametes, each having been produced by meiotic cell division. [5] [6] After growth from the zygote to the adult, cell division by mitosis allows for continual construction and repair of the organism. [7]
The vertex arrangement of the 16-cell honeycomb is called the D 4 lattice or F 4 lattice. [2] The vertices of this lattice are the centers of the 3-spheres in the densest known packing of equal spheres in 4-space; [3] its kissing number is 24, which is also the same as the kissing number in R 4, as proved by Oleg Musin in 2003.
The cell was first discovered by Robert Hooke in 1665 using a microscope. The first cell theory is credited to the work of Theodor Schwann and Matthias Jakob Schleiden in the 1830s. In this theory the internal contents of cells were called protoplasm and described as a jelly-like substance, sometimes called living jelly.
Cellular compartments in cell biology comprise all of the closed parts within the cytosol of a eukaryotic cell, usually surrounded by a single or double lipid layer membrane. These compartments are often, but not always, defined as membrane-bound organelles. The formation of cellular compartments is called compartmentalization.