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The number of mitochondria in a cell can vary widely by organism, tissue, and cell type. A mature red blood cell has no mitochondria, [19] whereas a liver cell can have more than 2000. [20] [21] The mitochondrion is composed of compartments that carry out specialized functions.
The cell nucleus (from Latin nucleus or nuculeus 'kernel, seed'; pl.: nuclei) is a membrane-bound organelle found in eukaryotic cells. Eukaryotic cells usually have a single nucleus, but a few cell types, such as mammalian red blood cells , have no nuclei , and a few others including osteoclasts have many .
Mitochondria are essentially universal in the eukaryotes, and with their own DNA somewhat resemble prokaryotic cells. Mitochondria are organelles in eukaryotic cells. The mitochondrion is commonly called "the powerhouse of the cell", [30] for its function providing energy by oxidising sugars or fats to produce the energy-storing molecule ATP.
Cell nucleus: A cell's information center, the cell nucleus is the most conspicuous organelle found in a eukaryotic cell. It houses the cell's chromosomes , and is the place where almost all DNA replication and RNA synthesis ( transcription ) occur.
The proportion of cell volume that is cytosol varies: for example while this compartment forms the bulk of cell structure in bacteria, [9] in plant cells the main compartment is the large central vacuole. [10] The cytosol consists mostly of water, dissolved ions, small molecules, and large water-soluble molecules (such as proteins).
The cytoplasm describes all the material within a eukaryotic or prokaryotic cell, enclosed by the cell membrane, including the organelles [1] and excluding the nucleus in eukaryotic cells. The material inside the nucleus of a eukaryotic cell and contained within the nuclear membrane is termed the nucleoplasm. The main components of the ...
Both organelles, the mitochondria and chloroplasts (in photosynthetic organisms), are compartments that are believed to be of endosymbiotic origin. Other compartments such as peroxisomes, lysosomes, the endoplasmic reticulum, the cell nucleus or the Golgi apparatus are not of endosymbiotic origin.
Plant cells lack centrioles or spindle pole bodies except in their flagellate male gametes, and they are entirely absent in the conifers and flowering plants. [4] Instead, the nuclear envelope itself appears to function as the main MTOC for microtubule nucleation and spindle organization during plant cell mitosis.