Beginning of Essay
As can be seen above, caffeine consists of two carbon/nitrogen rings with oxygen and methyl groups as substituents. The fused rings are similar to those in adenine only the substituents differ. Caffeine is found in coffee, tea, and many soft drinks. There is als ....

Middle of Essay
.... that caffeine will fit adenosine receptors as well as adenosine itself will. Thus, cyclic AMP remains active, rather than being broken down. Second among the effects of caffeine is phosphodiesterase inhibition. The phosphodiesterase class of enzymes includes a number of enzymes responsible for breaking down cyclic AMP, thus depriving the body of an energy supply. Caffeine fools phosphodiesterase into attacking it instead, which inhibits the breakdown of cyclic AMP. However, the concentration of caffeine required for this effect to become significant is sufficiently high that the adenosine blocking remains the dominant factor. The other two laborator ....