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Eukaryotic cells have a variety of internal membrane-bound structures, called organelles, and a cytoskeleton which defines the cell's organization and shape. The nucleus stores the cell's DNA , which is divided into linear bundles called chromosomes ; [ 19 ] these are separated into two matching sets by a microtubular spindle during nuclear ...
Prokaryotic cells are usually much smaller than eukaryotic cells. [3] Therefore, prokaryotes have a larger surface-area-to-volume ratio, giving them a higher metabolic rate, a higher growth rate, and as a consequence, a shorter generation time than eukaryotes. [3] Phylogenetic tree showing the diversity of prokaryotes. [56]
Eukaryogenesis, the process which created the eukaryotic cell and lineage, is a milestone in the evolution of life, since eukaryotes include all complex cells and almost all multicellular organisms. The process is widely agreed to have involved symbiogenesis, in which an archeon and a bacterium came together to create the first eukaryotic ...
Prokaryotes include bacteria and archaea, two of the three domains of life. Prokaryotic cells were the first form of life on Earth, characterized by having vital biological processes including cell signaling. They are simpler and smaller than eukaryotic cells, and lack a nucleus, and other membrane-bound organelles.
The cytoskeleton is a complex, dynamic network of interlinking protein filaments present in the cytoplasm of all cells, including those of bacteria and archaea. [2] In eukaryotes, it extends from the cell nucleus to the cell membrane and is composed of similar proteins in the various organisms. It is composed of three main components ...
Category. v. t. e. Cell biology (also cellular biology or cytology) is a branch of biology that studies the structure, function, and behavior of cells. [1][2] All living organisms are made of cells. A cell is the basic unit of life that is responsible for the living and functioning of organisms. [3] Cell biology is the study of the structural ...
Symbiogenesis (endosymbiotic theory, or serial endosymbiotic theory[2]) is the leading evolutionary theory of the origin of eukaryotic cells from prokaryotic organisms. [3] The theory holds that mitochondria, plastids such as chloroplasts, and possibly other organelles of eukaryotic cells are descended from formerly free-living prokaryotes ...
The two-domain system defines classification of all known cellular life forms into two domains: Bacteria and Archaea. It overrides the domain Eukaryota recognised in the three-domain classification as one of the main domains. In contrast to the eocyte hypothesis, which proposed two major groups of life (similar to domains) and posited that ...