Small molecules offer a significant advantage over classical genetic techniques in that they can serve as ‘conditional alleles’.  For example, a small molecule that targets a specific protein can be used to ‘knock out’ or inhibit that protein only at a certain point during the cell cycle or during an organism's developmental process.  In this approach small molecules act as ‘conditional alleles’ that can be used in a temporal manner to induce or inhibit a specific biological response, thus providing a method to selectively investigate cell signaling events within a narrow temporal window.  In this way chemical genetics has provided the means to answer biological questions that are difficult to study with standard genetic methods.  

Natural selection has taught us that biological systems find or create ways to adapt to exogenous forces or stressors.  Natural products are often the results of this survival mechanism.  These often highly potent small molecules encompass a diverse array of structural variation and biological activities. Historically, isolated compounds and extracts have been utilized as herbal remedies or drugs.  Initially, pharmaceutical companies utilized natural products as a source or lead toward new drug candidates.  Although the majority of these compounds lack the potential for use as drugs, biologists in recent years have found that natural products are useful for perturbing model cell systems.  As a class of compounds they offer a unique starting point for investigating biological systems.  Because they are created in a living system, they are often cell permeable and have specific biological targets.  Using structure activity relationships, via the analysis of analogs, natural products provide a starting point, from which to develop new synthetic biological probes and tools to understand cellular mechanisms.