Proto-oncogenes signal cells to grow and differentiate. However, they can become oncogenes due to mutations which result in the uncontrollable division of the cells, i.e. cancer. One way is a point mutation in a proto-oncogene. The consequence is changed protein product. Another way is gene amplification of DNA segment containing a proto-oncogene. As the result, the encoded protein is overexpressed. The third way is translocation. As the result of translocation, proto-oncogene can be controlled by the different promoter and expressed inappropriately.
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BOTONY:
any of the minute pores in the epidermis of the leaf or stem of a plant, forming a slit of variable width which allows movement of gases in and out of the intercellular spaces.
MEDICINE
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an artificial opening made into a hollow organ, especially one on the surface of the body leading to the gut or trachea.
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Answer:
1. All living organisms are composed of one or more cells.
2.The cell is the basic unit of structure and organization in organisms.
3. Cells arise from pre-existing cells.
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