I think life is spectacular and also very, very complex. Each living organism has three separate but intertwined aspects of its being. The first is its shape and structure, its morphology. There is something in us that shapes our ends, and our other body parts. The second is its biochemistry. There is both a commonality and a differentiation in the chemistry of living organisms. For example, grass has chlorophyll and you and I do not. The third is its operating system. This is much like the operating system of a computer. My first computer used MSDOS as its operating system, my present one runs Windows 7. There have been vast improvements in the capabilities of my computers over time but they all operated using fundamentally similar binary codes. It is the same in regard to all the different organisms and their differences in capabilities.
Going back to morphology (and including within it appearance and behavior), biological classification (taxonomy) and also mineral classification effectively had their beginnings with Carl Linnaeus (1707-1778). His three kingdoms were animal, vegetable, and mineral, so he can also be regarded as making a contribution to the game Twenty Questions. There are presently, though there weren’t always, five (or six, if you count viruses) kingdoms used in classifying organisms. There are also now two or three domains, which are classifications more inclusive than kingdoms.
When we turn to the chemistry of life we find the same pattern as we did with the shape and structure of organisms. For example, proteins, which are formed by genetic expression from twenty standard amino acids, are essential to all organisms and are used in virtually every cellular process. Proteins catalyze biochemical reactions; they have structural and mechanical functions; they are part of the scaffolds that give cells their shape. They also participate in immune responses; cell signaling, cell adhesion and cell division. Proteins are often modified after their formation to alter their chemical and physical properties by addition of non-amino molecules, and in the way they are folded.
In proteins we see order among complexity. We also see in protein the linkages in life. We need proteins yet we cannot create in our own bodies all the amino acids necessary for the formation of proteins. This means we have to eat other organisms that do contain the amino acids we need. Fortunately, readily available organisms from various parts of the biological classification can supply people, even with widely varying diets, the amino acids they need.
Now for another characteristic of proteins, the ones that are good for us must be folded correctly. Misfolded proteins are called prions and can cause various fatal diseases such as Creutzfeldt-Jakob disease in humans, or mad cow disease or scrapie in livestock. This shows us there is more to biochemistry than simply atoms assembled into certain molecules in a particular arrangement. We see that biochemistry has in both the width of life and the narrowness of necessity.
Each cell in our bodies (except for egg and sperm cells) contains about 40,000 protein-coding genes. This seems a very large number but it is less than microbiologists expected and actually only accounts for approximately 1.5 percent of the genome. The rest of the genome consists of regulatory DNA (deoxyribonucleic acid), non-coding RNA (ribonucleic acid), separators, and sequences whose functions are not known.
Things really get spectacular when we come to the numbers regarding our genomes, each of which contains a complete set of genetic information concerning us. Our mothers had an egg cell containing three billion base pairs and our fathers contributed a like number. These base pairs are contained within 23 chromosome pairs. Other organisms have different numbers of chromosome and base pairs but all life has at least some impressive number base pairs.
I started this post with morphology and ended with genomic biology. Morphology was the biology of the eighteenth and nineteenth centuries, including Linnaeus and Darwin. The twentieth century was the era of biochemical biology which tended to see life and its functions as products of organic chemistry. We are now in the period, possibly only at the beginnings, of genetic biology.
Life is a matter of spectacular complexity but common to it all is DNA and RNA. Although the Urey-Miller experiment showed that the production of amino acids and other organic chemicals could be done in simulated natural conditions, as far as I can tell no one has done an experiment producing nucleic acids. Even if they had, it would not probably not explain the coding, folding and other functions contained in the molecules as they are found in organisms.
I think the tasks ahead for microbiologists include arriving at a genomic theory of life to replace the present theory of evolution, and not to allow that catch-all explanation to be morphed into something called neo-Darwinism, and so to claim it now explains everything about life. Another task for genomic biologists is to show there is an actual process that takes matter and energy and in some way produces nucleic acid with a coding for some form of life.
I think those of us who are not microbiologists deserve a new theory of life based on the reality of what life is and how it works because life is truly, truly spectacular.