Regulation by Internal Factors

First let us consider regulation by internal factors, i.e. factors that are already present in the organism. In doing so we must distinguish between intracellular and intercellular regulation, as mentioned above. 

Up to now we have spoken only of regulation by internal factors. However, the situation within an organism is influenced quite substantially by external factors. Of the many external factors which can influence the growth and differentiation of plants, temperature and light are selected here. Moreover, we can point out only a few of the fundamentals relating to the mechanism of action of temperature and light in this section. 

Stomatal resistance is a critical factor affecting pollutant uptake. The resistance is determined by stomatal number, size, anatomical characteristics, and the size of the stomatal aperture. Little or no uptake occurs when the stoma is closed. Stomatal opening is regulated by internal C02 content, temperature, humidity, light, water availability, and nutrient status, particularly potassium. Research shows that K+ ions in the guard cells regulate the guard... 

While these external and internal factors already provided a difficult foundation, a routine investigation into the company by the US Food Drug Administration (FDA) identified areas of non-compliance with Good Manufacturing Practice (GMP) regulations. The resulting... 

In many cases of regulated protein degradation it was shown that ubiquit-ination is positively regulated by phosphorylation. This holds true also for endocytosis. Internalization of the a-factor receptor, for example, was shown to depend on specific serine residues in the cytoplasmic tail. They are found in a 9 amino acid motive, SINNDAKSS, which is essential for endocytosis. Mutant versions of Ste2 in which the three serine residues have been... 

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