>>12870>DNA is not the self promulgating, determining feature of biological life it is often made out to be.Nobody is saying DNA solely determines biological life today, because many other complicating factors have since been discovered. That's how science works - you learn more information and it builds on the theory. DNA is still the primary defining element of an organism in the sense that all other functions depend on the sequences in the DNA.
>If you needed a metaphor, you could say DNA is a collection of blueprints. The cell directs production by making them available to transcribing proteins.none of that means genes don't exist, it just means they are not sole determinants, which is not something mainstream biology argues.
>How often does that occur? The only significant prion disease i'm aware of is BSE.Not very often, because protein synthesis is successful in the vast majority of cases (99+% because protein synthesis is happening all the time in all living cells), but yes there are a lot of prion diseases. One of the most threatening ones is chronic wasting disease which is endemic in North American deer but can spread to other species and contaminates the land where the infected deer roam and die.
>I don't get why proteins being "constructed in a very specific way" is supposed to necessitate the existence of genes.Because the genes are what provides the instructions, as you put it "blueprints" for how to synthesize the proteins. For a given protein to synthesize
regularly and
consistently there has to be a sequence in the DNA that can be copied to produce those instructions for use. For every specific protein that can be produced there is a particular set of instructions. The specific sequence that produces that protein is the gene.
>Rather it seems to run counter to the concept, because their formation requires many factors beyond a DNA segment that is being transcribed and they don't show any genetic drift.The genetic information is what provides the instructions, and cells reproduce most of the distinct parts of themselves according to the code in the DNA (mitochondria have their own DNA, and some things need to be absorbed from outside the body, viruses, etc). Environment also affects this but invoking the other contents of the cell to discredit genes makes no sense because those cellular components - the organelles, the cell membrane, the cytoplasm, etc - are biologically produced in the cell according to the instructions in the nuclear DNA. Just because the DNA does not contain within itself the entire "factory" of biological production doesn't mean that it doesn't contain the instructions. The DNA needs to be in a cell in order for the instructions to be read and to be used, but it is still the home of the instructions.
>How do you reconcile the absence of homologous proteins in a species with evolutionary gradualism?This is a non-issue first of all (nowhere did I posit gradualism, which like its primary competitor punctuated equilibrium is an outdated model), but like I said above, the ingredients of proteins isn't just a product of evolutionary drift but also selection pressures, in particular the diet of the organism. An organism that gets more of a particular amino acid will be under pressure to substitute that amino acid over ones it gets less of, because that's advantageous. But more importantly the very idea that scientific theories need to be "reconciled" or else be rejected is completely wrongheaded. It's not unusual for scientific theories to at first seem in contradiciton because they are incomplete, only to be improved later. In the meantime they are valid insofar as they can be validat
ed by experiment, and if/when the theories are reconciled the previous data don't stop being true. But when physicists moved on from classical physics to quantum physics or from newtonian to relativistic physics the idea of gravity or electrons didn't stop being "correct." The models describing them got more accurate (and more sophisticated).