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Publicado: 30 de septiembre de 2012
eukaryotic cell
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A cell that contains membrane-bound compartments in which specific metabolic activities take place. Most important among these compartments is the nucleus, which housesthe eukaryotic cell's DNA. It is this nucleus that gives the eukaryote – literally, "true nucleus" – its name. Eukaryotic organisms also have other specialized, membrane-bounded structures,calledorganelles, which are small structures within cells that perform dedicated functions. Eukaryotic cells are typically 10 to 100 micrometers across, or about 10 times the size of prokaryotic cells. Origin of eukaryotic cells
The set of ideas most favored by biologists to explain how eukaryotic cells first came about is called the endosymbiotic theory. This theory is able to account well for thefact that two of the organelles found in eukaryotic cells, mitochondria and chloroplasts, have their own DNA that is completely distinct from the DNA housed in the nucleus. According to theendosymbiotic theory, the eukaryotic cell evolved from a symbiotic community of prokaryotic cells. Specifically, the mitochondria and the chloroplasts are what remains of ancient symbioticoxygen-breathing bacteria and cyanobacteria, respectively, whereas the rest of the cell seems to be derived from an ancestral archaean prokaryote cell.
The origin of the eukaryotic cell was a milestone in the evolutionof life. Although eukaryotes use the samegenetic code and metabolic processes as prokaryotes, their higher level of organizational complexity has permitted the development oftruly multicellular organisms. Without eukaryotes, the world would lack mammals, birds, fish, invertebrates, fungi, plants, and complex single-celled organisms.
Structure
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All eukaryotic cells have a number offeatures in common. These include:
* nucleus
* cytoplasm
* cell (plasma) membrane
* mitochondria
* endoplasmic reticulum
* Golgi apparatus
* ribosomes
* cytoskeleton...
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A cell that contains membrane-bound compartments in which specific metabolic activities take place. Most important among these compartments is the nucleus, which housesthe eukaryotic cell's DNA. It is this nucleus that gives the eukaryote – literally, "true nucleus" – its name. Eukaryotic organisms also have other specialized, membrane-bounded structures,calledorganelles, which are small structures within cells that perform dedicated functions. Eukaryotic cells are typically 10 to 100 micrometers across, or about 10 times the size of prokaryotic cells. Origin of eukaryotic cells
The set of ideas most favored by biologists to explain how eukaryotic cells first came about is called the endosymbiotic theory. This theory is able to account well for thefact that two of the organelles found in eukaryotic cells, mitochondria and chloroplasts, have their own DNA that is completely distinct from the DNA housed in the nucleus. According to theendosymbiotic theory, the eukaryotic cell evolved from a symbiotic community of prokaryotic cells. Specifically, the mitochondria and the chloroplasts are what remains of ancient symbioticoxygen-breathing bacteria and cyanobacteria, respectively, whereas the rest of the cell seems to be derived from an ancestral archaean prokaryote cell.
The origin of the eukaryotic cell was a milestone in the evolutionof life. Although eukaryotes use the samegenetic code and metabolic processes as prokaryotes, their higher level of organizational complexity has permitted the development oftruly multicellular organisms. Without eukaryotes, the world would lack mammals, birds, fish, invertebrates, fungi, plants, and complex single-celled organisms.
Structure
|
|
All eukaryotic cells have a number offeatures in common. These include:
* nucleus
* cytoplasm
* cell (plasma) membrane
* mitochondria
* endoplasmic reticulum
* Golgi apparatus
* ribosomes
* cytoskeleton...
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