Biochemical pathway, definition

How did the citric acid cycle come into being Although definitive answers are elusive, it is nevertheless instructive to speculate how this complicated central hub of metabolism developed. We can perhaps begin to comprehend how evolution might work at the level of biochemical pathways. 

The multiple reactions invoked on the biochemical pathway (i. e. between the beginning and the end of an autoimmunopathy) are definitely involved in the accumulation of other unknown intermediary products, which can in turn influence and manipulate a state of autoimmunopathy. 

The definition of oxidized fish oil-like aromas still leave fresh fish aromas undefined. Various freshly harvested fish have distinguishing aromas, but they also are characterized by a common plant-like, seaweed-like aroma. Thus, compounds and reaction pathways different from random autoxidation appear likely and reasonable. Even conflicting descriptions of fishy odors, i.e., including roles for volatile amines (2 19) and sulfur compounds (20-22), can be accommodated by the hypothesis that previously unrecognized biochemical reactions yield characterizing fresh fish aromas. These premises led to investigations (23-26) which have resulted in the identification of a group of enzymically-derived volatile aroma compounds that contribute fresh, plant-like aromas to freshly harvested fish (Table I). 

For purposes of this chapter, we define a pathway as a description of the mechanism of the typical process by which a cellular or organismic function is realized. This definition makes two points. First, a pathway is not a mechanism, but a description of mechanisms, that is, it exists as a model subject to our investigative needs and not as an entity itself. Second, a pathway must have functional interpretations, that is, it must correspond to a goal or need we can identify in the cell or organism. Thus this definition does not provide a purely objective criterion but tosses the problem into the laps of people who want to define function at the cellular or organismic level. It also removes from consideration any sequence of biochemical interactions that do not have such an interpretation. 

---