Energy metabolism types with representative organisms

Table 7.10 Main Types of Energy Metabolisms with Examples of Representative Organisms.

Table 5.4 Main types of energy metabolism with examples of representative organisms.

The student should be aware that a pathway is essentially a conceptual model developed by biochemists in order to represent the flow of compounds and energy through metabolism. Such models are simply ways of trying to explain experimental data. A potential problem in representing metabolic pathways as in Figure 1.1 is that there is an implication that they are physically and/or topographically organized sequences. This is not necessarily true. With some exceptions (described in Section 1.3), most enzymes are likely to be found free within the cytosol or a compartment of a cell where reactions occur when an enzyme and its substrate meet as a result of their own random motion. Clearly this would be very inefficient were it not for the fact that cells contain many copies of each enzyme and many molecules of each type of substrate. 

---