A commenter in another thread prompted this. I didn’t approve the comment because it was so impoverished but thought the discussion warranted a thread of its own. The commenter basically said that 30,000 proteins w/regulatory regions is enough – a mere fraction of the DNA in a human egg – implying that plenty of DNA can be functionless junk.
While that number of regulated proteins might possibly be enough to define myriad cell types and tissue types there is an awful lot more required. The list of things I can think of (which is likely not complete) includes:
1) cell types
2) tissue types
3) organs
5) body plan
6) autonomic control system
7) instinctive behaviors
Since complex system design is what I did for a living I usually think in terms analogous to human designed systems and the information required in their specification. Let’s take the space shuttle for a comparison. Proteins would be equivalent to simple basic raw materials – plastics, metals, ceramics, and the like. Cell types would be equivalent nuts, bolts, fabrics, tiles, and other formed, milled, & molded parts. Tissue types would be equivalent to basic functional assemblages tubes, pipes, wires, nozzles, panels, tanks, transisters, batteries, and things of that nature. Organs would be even larger assemblages of like computers, control surfaces, engines, pressure locks, hatches, windows, atmosphere controls, and etcetera. Body plan would be the precise arrangement of larger assemblies into a specific functional whole. Autonomic controls would be mostly electro-mechanical regulators for gas flows, fuel flows, hydraulics, electrics, and other simple automated functions. Instinctive behaviors would be analagous to flight/mission command & control software.
Anyone that’s done any complex system design knows the materials are just a small part of the specification. Even basic assemblies are just more or less standardized parts and don’t require comparatively much specification. The real complexity lies in the precise arrangement and how they all work together. Anyone familiar with the hundreds of volumes of specifications in a complex system like the space shuttle has a feel for how much information it takes. If every last base pair of DNA in the human genome was utilized I still don’t think it’s nearly enough. It isn’t anywhere near enough for a space shuttle and a human is far more complex than a space shuttle. I suspect far more of the cell structure, often called epigenetic information, is required for the complete specification. That makes trillions more atoms potentially usable for information storage and it’s all heritable as each daughter cell is more or less a faithful copy of its parent cell.