Metabolism
From EvoWiki
Metabolism is organisms' way of gaining useable energy (ectropy), in other words, of losing entropy. It means chemically transforming substances (and light, in the case of plants) into the organism's own tissue and into waste products. Because of the Second Law of Thermodynamics, the output entropy has to be higher than the input entropy (the input useable energy has to be lower that the output useable energy).
It is perfectly normal for an organism to "get more complex" (gain useable energy) simply by the process of metabolism. The entropy decrease (or useable energy increase) creationists see in the increasing complexity over evolutionary lineages is tiny compared to the amount of useable energy gained by the metabolism of the organisms involved in the process during the same time.
For example, if a cat eats a mouse, it would gain enough useable energy to build a new cat (the size of the mouse) from scratch, if the metabolic processes didn't lose useable energy on the way. After all, mice and cats have about the same "complexity" per weight. In reality, the cat needs to eat several mice to accomplish that feat. That is exactly what a female cat does when pregnant: taking useable energy from mice and building kittens with it.
Metabolism can be divided into two categories: anabolism and catabolism.
Anabolism may be thought of as the constructive phase. Anabolism involves the synthesis of complex organic molecules from simpler organic molecules or inorganic constituents. The process is endothermic. Simple molecules + energy ==> complex molecules. The energy for the process can be:
1. solar energy (light) via photosynthesis for autotrophs;
2. chemical energy from the external environment for chemotrophs and lithotrophs;
3. chemical energy from catabolism for organotrophs.
Catabolism involves the breakdown of complex organic molecules to release energy and produce either smaller “building block�? organic molecules or waste products. The process is exothermic and may proceed by either aerobic or anaerobic processes.
Non-biogenic or prebiogenic metabolism (or protometabolism) has been hypothesized to occur on complex iron sulfide “bubbles�? in hydrothermal vent environments. See the Origin of Life web site, University of Glascow.
