(August 2003) Cells show an astounding awareness of the environments in which they find themselves, actually adapting their behavior to changing surroundings. The key to this ability is a constant sampling of the multitude of molecules found in their environments, many of which are signals that convey information to the cell [1]. To do communicate with their environment, they employ a large array of molecules that allow signals to be sent, received, deciphered and responded to. These molecules are generally referred to as “signaling molecules [2].” Categorization of these molecules on the most general level is based on whether they…

(August 2003) As early as the 19th century it was known that phosphates could be bound to proteins. Most examples of these ‘phosphoproteins’ were found in milk (caseins) and egg yolk (phosvitin) and were simply considered a biological method of providing phosphorus as a nutrient. Therefore, the existence of phosphoproteins was considered a consequence of metabolic reactions, and nothing more, for almost a century after their discovery [1]. In the 1950’s this all began to change as phosphoproteins began to emerge as key regulators of cellular life. An initiating factor of this emergence occurred in 1954, when an enzyme activity…

(August 2003) Conversation in the biological world is quite natural. Even on the level of the cell, a busy broadcast of communications is occurring; a fact which has caught the attention of biologists. Today, one of the hottest areas in cell biology research is the study of ‘signal transduction’. Signal transduction is the study of how a cell communicates [1]. Every cell is able to communicate through having evolved the ability to produce, recognize, interpret and respond to signals in its environment. The word ‘signals’ in this context refers to nothing more than chemical molecules that are floating around. Cells…

The behavior of a cell often relies on the chemical signals it is exposed to in its environment. In general, two types of chemical signals can be found floating through the cellular environment: water-soluble (hydrophilic) molecules or fat-soluble (hydrophobic) molecules. Both are important components of cellular communication and physically interact with cellular structures to facilitate this function. In virtually every case, the cellular structures that these chemical signals interact with are receptor proteins. Receptors and the Surface of a Cell A cell is surrounded by a membrane, which forms a barrier between the inside and outside of the cell. This…

(August, 2003) The first inklings of genetic theory can be traced back to a common human experience: the recognition that a child has features similar to those of its parents. This ancient observation is actually one of the cornerstones of genetics and its subsequent offspring, molecular biology. For centuries there was little evidence beyond the anecdotal that transmitted inheritance was a reasonable theory. Though it seemed sensible that a child with the same appearance as its parents likely received these characteristics from them, little evidence supported the notion and instead a good deal of confusion surrounded it. Part of the…