Examples of growth factor in the following topics:
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- The ligands that promote cell growth are called growth factors.
- Most growth factors bind to cell-surface receptors that are linked to tyrosine kinases.
- Signaling pathways control cell growth.
- Further studies have indicated that 30 percent of cancer cells have a mutation in the RAS gene that leads to uncontrolled growth.
- If left unchecked, uncontrolled cell division can lead tumor formation and metastasis, the growth of cancer cells in new locations in the body.
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- The process of cellular differentiation is regulated by transcription factors and growth factors, and results in expression or inhibition of various genes between the cell types, thereby resulting in varying proteomes between cell types .
- The ability of transcription factors to control whether a gene will be transcribed or not that contributes to specialization and growth factors to aid in the division process are key components of cell differentiation.
- Mechanics of cellular differentiation can be controlled by growth factors which can induce cell division.
- In asymetric cell division the cell will be induced to differentiate into a specialized cell and the growth factors will work in tandem.
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- Body growth is controlled by growth hormone (GH), produced by the anterior pituitary, and IGF-1, whose production is stimulated by GH.
- GH also stimulates, through another pathway, the production of insulin-like growth factor 1 (IGF-1), a hormone homologous to proinsulin.
- GH release is stimulated by growth hormone-releasing hormone (GHRH) and is inhibited by growth hormone-inhibiting hormone (GHIH), also called somatostatin.
- Oversecretion of growth hormone can lead to gigantism in children, causing excessive growth.
- Insulin-like growth factor 1 (IGF-1) is activated by growth hormone and also allows formation of new proteins in muscle cells and bone.
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- Increased transcriptional activation of genes result in alterations of cell growth leading to abnormal gene expression, as seen in cancer.
- Mutations that activate transcription factors, such as increased phosphorylation, can increase the binding of a transcription factor to its binding site in a promoter.
- This could lead to increased transcriptional activation of that gene that results in modified cell growth.
- One such example is the overexpression of the epidermal growth factor receptor (EGFR) in a subset of breast cancers.
- The EGFR pathway activates many protein kinases that, in turn, activate many transcription factors that control genes involved in cell growth.
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- The two most important abiotic factors affecting plant primary productivity in an ecosystem are temperature and moisture.
- Environments with the greatest amount of biomass have conditions in which photosynthesis, plant growth, and the resulting net primary productivity are optimized.
- Together, these factors lead to the maximal amount of carbon dioxide (CO2) moving into the plant, resulting in high biomass production.
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- External factors can influence the cell cycle by inhibiting or initiating cell division.
- An event may be as simple as the death of a nearby cell or as sweeping as the release of growth-promoting hormones, such as human growth hormone (HGH).
- Another factor that can initiate cell division is the size of the cell; as a cell grows, it becomes inefficient due to its decreasing surface-to-volume ratio.
- This was a result of a lack of Human Growth Hormone.
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- Eventually, the growth rate will plateau or level off.
- The formula we use to calculate logistic growth adds the carrying capacity as a moderating force in the growth rate.
- Thus, the exponential growth model is restricted by this factor to generate the logistic growth equation:
- A graph of this equation yields an S-shaped curve ; it is a more-realistic model of population growth than exponential growth.
- Its growth levels off as the population depletes the nutrients that are necessary for its growth.
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- Population regulation is a density-dependent process, meaning that population growth rates are regulated by the density of a population.
- In population ecology, density-dependent processes occur when population growth rates are regulated by the density of a population.
- For example, during intra- and interspecific competition, the reproductive rates of the individuals will usually be lower, reducing their population's rate of growth.
- Many factors, typically physical or chemical in nature (abiotic), influence the mortality of a population regardless of its density.
- In real-life situations, population regulation is very complicated and density-dependent and independent factors can interact.
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- In normal cells, some genes function to prevent excess, inappropriate cell growth.
- The p53 protein itself functions as a transcription factor.
- Overexpression of the oncogene can lead to uncontrolled cell growth because oncogenes can alter transcriptional activity, stability, or protein translation of another gene that directly or indirectly controls cell growth.
- Myc is a transcription factor that is aberrantly activated in Burkett's Lymphoma, a cancer of the lymph system.
- When mutated, proto-oncogenes can become oncogenes and cause cancer due to uncontrolled cell growth.
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- With knowledge of this age structure, population growth can be more accurately predicted.
- Some developed countries, such as Italy, have zero population growth.
- All of the factors above also have an impact on the average life expectancy.
- The percent growth rate of population in different countries shows that the highest growth rates are in underdeveloped regions of Africa and Asia.
- The slow-growth model shows that the proportion of individuals decreases steadily with age.