Thursday, February 09, 2006
Physicists question whether there are "universals" in biology. One reason is that the prevailing theory of biological evolution postulates a random walk to each new adaptation. In the last 50 years, molecular genetics has revealed features of DNA sequence organization, protein structure and cellular processes of genetic change that suggest evolution by natural genetic engineering. Genomes are hierarchically organized as systems assembled from DNA modules, which themselves generally constitute systems at lower levels. Each genome is formatted and integrated by sequence elements that do not code for proteins. These formatting elements constitute codons in multiple genetic codes for distinct functions such as transcription, replication, DNA compaction and genome distribution to daughter cells. Consequently, the genome has a computational system architecture. Proteins are systems composed of functionally distinct domains connected in polypeptide chains. Whole-genome sequencing indicates that rearrangement of genetic modules plus duplication and reuse of existing genomic systems are fundamental events in evolution. Studies of genetic change show that cells possess mobile genetic elements and other natural genetic engineering activities to carry out the necessary DNA reorganizations. Natural genetic engineering functions are sensitive to biological inputs, and their non-random operations help explain how novel system architectures can arise in evolution.
Technorati tags: genome system architecture, signal transduction, cellular computation, natural genetic engineering, mobile genetic elements,dna, biology, evolution, shapiro