Conrado F. Asenjo
School of Medicine of Puerto Rico Son Juon, Puerto Rico
Universilv
II
Combustion Versus Biological Oxidation
An analogy which has proved useful in conveying to students the difference between comhustion and biological oxidation, is the behavior of a small plastic toy.' Inside the hollow frame is a wheel and attached to its periphery are several carefully designed rubber suckers. These suckers allow the toy to stick, one sucker a t a time, to a llat surface. The axle of the wheel is connected to a spring, which when distorted by unwinding a cord attached to the axle, accumulates energy. The energy accumulated in the spring is released with a bang when the cord is released. This is equivalent to what happens in rapid combustion; that is, a large quantity of energy is released in a very short period of time, thus attaining explosive violence with the liberation of heat. On the other hand, when the string is unwound and the toy is placed against a vertical flat surface, such as a blackboard, the energy accumulated in the spring is released gradually (instead of being released suddenly), driving the suckers according to a plan and actually allowing the toy to olin~h against the vertical surface, thus performing useful work as though endowed with life. This slow and
orderly use oi energy is just what takes place during hiological oxidation in the living cell. This simple demonstration illustrates dramatically the difference between energy liberated rapidly and randomly, and therefore wastefully, and energy liberated slowly and purposefully, and therefore usefullv.
Top view of toy. 1
Tigrett Industries, Jackson, Tennessee
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Journol of Chemicol Education
Lower view ~ h o w i n grubber wckerr ond wheel o r l e with rape and spring attached.
