[Thank you to Elizabeth Liddle, the admins and the mods for hosting this discussion.]
I’ve long suspected the 3.1 to 3.5 gigabases of human DNA (which equates to roughly 750 to 875 megabytes) is woefully insufficient to create something as complex as a human being. The problem is there is only limited transgenerational epigenetic inheritance so it’s hard to assert large amounts of information are stored outside the DNA.
Further, the question arises how is this non-DNA information stored since it’s not easy to localize, in fact, if there is a large amount of information outside the DNA, it is in a form that is NOT localizable, but distributed and so deeply redundant that it provides the ability to self-heal and self-correct for injury and error. If so, in a sense, damage and changes to this information bearing system is not very heritable since bad variation in the non-DNA information source can get repaired and reset, otherwise the organism just dies. In that sense the organism is fundamentally immutable as a form, suggestive of a created kind rather than something that can evolve in the macro-evolutionary sense.
We often hear of genomics, but there are other -omics. There is proteomics, transcritonomics, lectinomics, and who knows what else which fall under the vague heading of epiginomics. If there is an immutable epigenetic kernel for each created kind, then this kernel will resist macro evolvability (like say from bacteria to a eukarya).
There are about 215 cell types in the human, and even supposing an average of a mere 5 developmental stages for each cell type, that’s over a thousand different transcriptomes in the human. The ENCODE consortium tracks only 150 or so transriptomes, and most are for cell in the cancerous stage. Where is the information stored to decide how to dice, splice, rna-edit RNAs, and postranslationally change proteins? ENCODE tracks some of this epiginomic data, but it’s only the tip of the iceberg. In fact, it could be argued each of the 200 trillion cells in an adult human has a slightly different transcriptome and proteome.
What other information storage mechanisms are there aside from DNA? It would have to be fairly fault tolerant so that you can’t knock out large portions of the system, and the information can be re-covered, much like having 100 backup hard-drives. One, and likely not the only information storage device, is implemented by the sugar code.
This link describes how the pharmaceutical industry has invested already 300 million dollars related to the sugar code, and how a mere 3 hexoes has the specificity of about 30 bits ( log2( 10^9) ).
Only God knows how all the information could be stored outside of the DNA complex, but we have hints that for sure there is lots of memory storage capacity outside the DNA. The memory stored through the sugar code might only be one of the many mechanisms through which information is stored in the cell.
Here is another paper:
Analysis of the genome and proteome assumes the focus of attention in efforts to relate biochemical coding with cell functionality. Among other chores in energy metabolism, the talents of carbohydrates to establish a high-density coding system give reason for a paradigmatic shift. The sequence complexity of glycans and glycan-processing enzymes (glycosyltransferases, glycosidases and enzymes introducing substituents such as sulfotransferases), the growing evidence for the importance of glycans from transgenic and knock-out animal models and the correlation of defects in glycosylation with diseases are substantial assets to portray oligosaccharides as code words in their own right. Matching the pace of progress in the work on glycoconjugates, the increasing level of refinement of our knowledge about lectins (definition of this term: carbohydrate-binding proteins, excluding sugar-specific antibodies, receptors of free mono- or disaccharides for transport or chemotaxis and enzymes modifying the bound carbohydrate) epitomizes the sphere of action of the sugar code (functional lectinomics). It encompasses, among other activities, intra- and intercellular transport processes, sensor branches of innate immunity, regulation of cell-cell (matrix) adhesion or migration and positive/negative growth control with implications for differentiation and malignancy. The Q & A approach taken in this review lists a series of arguments in a stepwise manner to make the reader wonder why it is only a rather recent process that the concept of the sugar code has taken root in deciphering the mechanistic versatility of biological information storage and transfer.