From: Henry Baker <hbaker1@pipeline.com> Re biological Rube Goldberg: I disagree vehemently. The more I learn of DNA, RNA, proteins, signalling, etc., the more impressed I am. For example, the process of mere _copying_ of DNA operates very close to the thermodynamic limit -- i.e., it would be very difficult to design _any_ system for copying DNA that produced less waste heat than our own DNA copying.
--Exactly wrong. DNA copying is done with rechecking and with use of ATP->AMP not ADP so it can get extra certainty. In other words it intentionally uses both extra energy and extra chemical steps. Many biochemical reactions in fact ARE reversible (e.g. fructose <--> glucose interconversion) and hence consume zero energy. But DNA copying is not one of them.
If our DNA copying were any less thermodynamically efficient, and we continued to copy at the same rate, our dividing cells would fry themselves like a fried egg.
--utter bull. DNA copying is a very small expenditure in human cells compared to other stuff.
Most evolutionary biologists will tell you that _none_ of the DNA is truly "junk". The proof: if it weren't important, it would relatively quickly disappear after a few generations.
--complete bull. DNA actually is expensive in bacteria and viruses, and they have little or no junk. But in eukaryotes like us, DNA is a tiny expenditure relatively speaking so we can afford lots of junk. By the way, you just "proved" microsoft windows is small and compact, not bloated.
Several biologists have proposed that complex organisms have lots of DNA as a form of "diagonalization": all of its siblings with less DNA didn't survive. This is akin to comparing the power of Turing Machines with more or less tape: those with "more" tape can simulate _all_ Turing Machines with "less" tape and do something different.
--you are totally confused. (And if you are right re "several biologists", they are confused too.)
For example, some of our DNA encodes experiences with viruses, some of which may be long extinct or at least dormant. Yet if that virus suddenly shows up, there are at least some fraction of humans that will survive.
--some of our DNA encodes viruses that incorporated themselves into our DNA and are now carried along for the ride for free inside us, where they are incurable since part of us. Further, some our DNA is "self replicating elements" which in fact multiply WITHIN our DNA; they are "out for themselves" not you. Somewhat like cancer but at a smaller size and longer time scale. This is (I suspect) the main reason closely related species have way different amounts of junk and that much of our junk is repeating sequences.
Plants (which typically don't move) seem to require more DNA than animals (which do move). One can speculate that plants have to sit there and take every insult, while animals can avoid the insult by moving and even emigrating when necessary.
--plants do a lot more chemistry than animals, so they need more genes (which describe chemistry). You can't synthesize many amino acids, fats, and vitamins you need because you lack the genes. Plants do not have that luxury. Animals can't do photosynthesis, even though it'd clearly be beneficial if they could. --In this post I am repeating the usual bio- philosophy & refuting weird myths posted by HB. The alleged new "it aint junk" philosophy to some extent must overthrow the old bio philosophy, but I'd like to know what is wrong with the old arguments, because they sure mostly are not wrong.