Adhesion Molecules-28

Aging-9

Agricultural Biotechnology-37

Angiogenesis-29

Antisense-4

Apoptosis-49

Atherosclerosis-12

Autoimmunity-69

Bacterial Virulence-18

Bioinformatics-13

BioMaterials-18

Biosurfactants-1

Biotechnology-99

Cancer Genetics-25

Cancer Metastasis-19

Cell Biology-16

Cell Cycle-34

Cell Metabolism-327

Channels and Transporters-79

Chaperones-11

Circadian Rhythms-13

Coagulation-14

Cytokines/Growth Factors-52

Development-223

DNA-56

DNA Surveillance and Repair-42

Drug Design-17

Endocrine-66

Evolution-33

Extracellular Matrix-30

Gastroenterology-52

Gene Expression-178

Gene Therapy-53

Heart-61

Heat Shock Proteins-19

Hematology-11

Immunology-93

Infectious Disease-72

Ischemia-Reperfusion-33

Leptin and Leptin Antagonists-1

Medical-7

MHC-17

Mitochondria-17

Molecular Biology-7

Molecular Complexes and Signaling-1

Nanomedicine-30

Neurodegenerative Disease-72

Neuropharmacology-112

Neuroscience-38

Nucleus-15

Oncogenes-8

Oncology-87

Parasitic Disease-12

Pharmacogenomics-14

Prebiotic Evolution-1

Protein-12

Reproductive Biology-59

RNA-152

Signal Transduction-186

Stem Cells-80

Surgery-37

T-Cell Activation-12

Tissue Engineering-116

Transplant-51

Vaccines-82

Viruses-85

Chapter category: Evolution

The Invariance Concept

Chapter authors:
Christian Schwabe

Tucked away, if it were possible, within the hollow of the tip of a dart gun needle aimed at man or beast one could make a memorable discovery. Just a moment after skin penetration the overwhelming impression would be ‘sameness’. A human, a pachyderm, a mouse, a rat, donkey, ape, in all cases the first experience is the epidermis, then the dermis, a layer of fat and collagen followed by muscles and sometimes a hard landing on a bone. If the needle were fine enough to penetrate the cell membrane and the nuclear envelope, the likeness would stretch to almost all of life because one would see strings of ATCGTACGCGG— as far as the eye reaches. How can the core of everything be so alike when creatures are as different as elephants and humming birds or tunicates and pigs? By reflex most biologists will point to a common ancestor that lived during the Hadean.^{1, 2} The new model suggests that the common ancestor did not live but that the universality of the physics that underlies chemistry had played the role of the pluri-potent ancestor.³ The number of possible chemical compounds is nearly limitless which raises questions as to how fundamental mechanisms could have come out so uniform.

It is a peculiar type of restriction that dominated the biogenesis scene. The first phase is carbon chemistry of the Miller-Urey type which led to the production of nucleic acids and amino acids among other molecules.⁴ Nucleic acids were the gate, the nozzle through which everything that would be part of life needed to pass and from experience we know about the tendency of chemistry to favor, above other compounds, the production of these biomolecules. Passive selection of constituents continued, guided only by what is thermodynamically favorable, until the first stages of self-replication became important. It does not take much imagination to see that nothing had a chance in competition with nucleic acids. Other compounds formed crystalline structures of billions of molecules but without the potential to produce informative defects. Errors in crystalline structures are too rare to carry the amount of information that living systems require.⁵ In contrast, the structure of nucleic acid is semi-crystalline but has an error (information) at every level of the helix. Life is built from the "memory out" toward the periphery and since the memory always reads [(A)x (T)x (C)y (G)y ] the nucleic acids in widely separated origins did not look much different. Nucleic acids work like the monotonous binary code tape of a "Turing Machine", a reading device that gives patterns of zeros’ and ones’ to which a meaning can be attached only after one decides what the blocks of symbols are to represent. The 4 bits of our nucleic acids, A, T, C, G provide a greater information density than a Turing tape and therefore a much shorter DNA string is sufficient to spell out a structure so complex that the most refined feature of the living world, the human brain, cannot comprehend it.

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