Therefore, as organic chemists, we use chemically-based biotechnology and continue to add other techniques that are not only applicable but in some cases requisite: fluorescence sorting and probing; recombinant DNA technology; cloning; plasmid construction. Organic chemistry approaching 100% con-combinatory procedures; the polymerase chain reaction (PCR); all of the latest separation and spectroscopic methodology with computer analysis; and the generous use -- as reagents -- of bacteria, fungi, enzymes, whole cells, and ground liver microsomes, inter alia.

1.1.5 Inter-Disciplinary Area between Chemistry and Biology

1.1.5.1. Biologically Relevant Small Molecules:

One such example is caffeine: Caffeine's principal mode of action is as an antagonist of adenosine receptors in the brain: related to bases.

Figure 1.2: Chemical Structure of Caffeine and Adenosine

[Antagonist:-  An antagonist is a character, group of characters, or an institution, which represents the opposition against which the protagonist must contend. In other words, 'A person, or a group of people who oppose the main character, or the main characters. In the classic style of story where in the action consists of a hero fighting a villain, the two can be regarded as protagonist and antagonist, respectively. The antagonist may also represent a major threat or obstacle to the main character by their very existence, without necessarily actively targeting him or her.
The stimulation of A1 adenosine receptors inhibits adenylcyclase and decreases intracellular cyclic AMP. The inhibition of these receptors leads to the opposite effect, i.e. an increase in adenylcyclase activity. Caffeine has the selective ability to antagonize the actions of adenosine.]

1.1.5.2 Cofactor Chemistry – Pyridinium Ions (e.g. NADH):

Figure 1.3: Chemical Structure of NAD and NADH