As creatures used to regarding ourselves as exceptional, humans must surely be humbled to realize that the instructions, for making one of our own, reside in a molecule so simple that scientists, for a very long time, did not believe could possibly contain enough information to build even a simple cell. But a large body of evidence, built up over the past century, supports Larison Cudmore’s assertion that the information for making you and me (and all the other kinds of living things in the world) is encoded in DNA. Tying in with classical genetic observations about how characteristics are passed on from one generation to the next, the discovery that there was a molecule that carried this information altered forever how people thought about heredity.
The elucidation of the structure of DNA provided greater insights into how traits might be encoded in a molecule, and the ways in which the information is used by cells. As we learn more about this topic, scientists have remarked on how the information in our DNA resembles the programs that drive computers. While this analogy is a simplification, there is definitely it is useful, with information in our DNA directly serving as stored information that determines the properties of the proteins that operate in cells and whole bodies. The analogy from stored information to accessed and ‘read’ information to functional machines is one many of us can relate to.
If this sounds strange, it is even more intriguing to realize DNA is copied and passed on from cell to cell, from one generation to the next. There is an unbroken line of inheritance from the first cell to every organism alive today.
The subject of biochemistry includes extensive consideration of structures in biology and also reactions (metabolism). But it also, importantly, includes informational considerations. In this way biochemistry is different from the other subdisciplines of chemistry, because it involves the essence of life: reproduction, the propagation of itself. For this to occur information must be passed around within and between cells.
Genetic information, its storage, how it is read and interpreted, and gives rise to the cellular activities that we can observe is a major subject of this chapter. Another kind of information is also considered, which is the molecular information that cells receive from, and send to, each other. The interplay of these two kinds of information is responsible for the form and behavior of all living organisms.