Onkogen

Oncogenes (literally cancer genes) are parts of the genome of a cell that promote the transition from the normal growth behavior of the cell to unrestrained tumor growth. The "gen" in oncogenes is not used in the sense of "producing" or "promoting" as used in the words carcinogen or mutagen, but derives directly from the word gene as part of the genotype. Edit ProtoonkogeneQualtext

Oncogenes are caused by changes in gene sequences (mutations) that play a role in normal cell growth, cell division and cell differentiation. The so-called proto-oncogenes are precursors of oncogenes and are converted into the carcinogenic form (the oncogene) by harmful influences (ionizing radiation, chemical substances or viruses). Today, more than 100 (as of 2004) proto-oncogenes are known. All cell cycle control genes are potential proto-oncogenes because their alteration or dysfunction can mean loss of control over cell division.

Proto-oncogenes are divided into several groups using the proteins encoded by them:

Protooncogenes are normal genes that occur in every cell and encode proteins that control and control the growth, division and differentiation of a cell. Many components that affect the growth of a cell can be viewed as proto-oncogenes. If such a gene is mutated, loss of function usually occurs, cell division is no longer promoted, and the cell is no longer able to divide. This usually leads to programmed cell death, the so-called apoptosis, which is not a problem for the organism, since there are normally enough other divisible cells in the neighborhood. There is also the possibility that the cell division is promoted by the mutation of the proto-oncogene. It can happen that a growth gene under the influence of a promoter, which is normally strongly activating, occurs due to chromosomal rearrangements. For example, For example, the promoters of the immunoglobulins are able to activate protooncogenes to oncogenes and thus contribute to the development of tumors. Weblinks Edit sourcetext

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