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The nuclear envelope, also known as the nuclear membrane, [1] [a] is made up of two lipid bilayer membranes that in eukaryotic cells surround the nucleus, which encloses the genetic material. The nuclear envelope consists of two lipid bilayer membranes: an inner nuclear membrane and an outer nuclear membrane. [ 4 ]
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 nuclear envelope (membrane), a defining characteristic of the eukaryotic cell, was suggested to have arisen as an adaptation for segregating the original archaeal host DNA genome away from the proto-mitochondria, the main source of damaging reactive oxygen species.
The nuclear envelope of a typical mammalian cell contains 3000–4000 pore complexes. If the cell is synthesizing DNA each pore complex needs to transport about 100 histone molecules per minute. If the cell is growing rapidly, each complex also needs to transport about 6 newly assembled large and small ribosomal subunits per minute from the ...
The cytoplasm is also found in all known cells while nucleoplasm is only found in eukaryotic cells, as prokaryotic cells lack a well-defined nucleus and membrane-bound organelles. Additionally, during cell division , the cytoplasm divides during cytokinesis , while the nucleoplasm is released with the dissolution of the nuclear envelope ...
The nuclear lamina is a dense (~30 to 100 nm thick) fibrillar network inside the nucleus of eukaryote cells. It is composed of intermediate filaments and membrane associated proteins. Besides providing mechanical support, the nuclear lamina regulates important cellular events such as DNA replication and cell division.
The cell envelope comprises the inner cell membrane and the cell wall of a bacterium. In Gram-negative bacteria an outer membrane is also included. [ 1 ] This envelope is not present in the Mollicutes where the cell wall is absent.
In cells where the nuclear membrane fragments into non-ER vesicles during mitosis, a Ran-GTP–dependent pathway can direct these discrete vesicle populations to chromatin where they fuse to reform the nuclear envelope. [19] [16] In cells where the nuclear membrane is absorbed into the endoplasmic reticulum during mitosis, reassembly involves ...