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Cell division is the process by which a parent DNA replication.
For simple unicellular organisms[Note 1] such as the
Multicellular organisms replace worn-out cells through cell division. In some animals, however, cell division eventually halts. In humans this occurs on average, after 52 divisions, known as the Hayflick limit. The cell is then referred to as senescent. Cells stop dividing because the telomeres, protective bits of DNA on the end of a chromosome required for replication, shorten with each copy, eventually being consumed, as described in the article on telomere shortening. Cancer cells, on the other hand, are not thought to degrade in this way, if at all. An enzyme called telomerase, present in large quantities in cancerous cells, rebuilds the telomeres, allowing division to continue indefinitely.
Cells are classified into two main categories: simple, non-nucleated prokaryotic cells, and complex, nucleated eukaryotic cells. By dint of their structural differences, eukaryotic and prokaryotic cells do not divide in the same way. Also, the pattern of cell division that transforms eukaryotic stem cells into gametes (sperm cells in males or ova – egg cells – in females) is different from that of the somatic cell division in the cells of the body.
The primary concern of cell division is the maintenance of the original cell's genome. Before division can occur, the genomic information that is stored in chromosomes must be replicated, and the duplicated genome must be separated cleanly between cells. A great deal of cellular infrastructure is involved in keeping genomic information consistent between "generations".
Cell division has been modeled by finite subdivision rules.[7]
[6] A human being's body experiences about 10,000 trillion cell divisions in a lifetime.[5]
Cancer, Greek language, Allium, Apoptosis, Protein
Lung cancer, Breast cancer, Colorectal cancer, Medical imaging, Prostate cancer
Religion, United Nations, Culture, Agriculture, Technology
Cancer, DNA repair, Death, Longevity, Life extension
Species, Mitosis, Centromere, Chromatin, DNA replication
Rna, Gene, Cell nucleus, Protein, Chromosome
Saccharomyces cerevisiae, Gene, Protein, Cytokinesis, Cell cycle
Mitosis, DNA replication, Apoptosis, Cdc25, S phase
Peer review, Oclc, Microbiology, American Society for Microbiology, Iso 4
Medical Subject Headings, Anaphase, Meiotic prophase i, Chromosome pairing, Synaptonemal complex