Macromolecular explanations

The reason is basically the same story we learned above about why the kinds of functional biology cannot be identified with those of molecular biology. Because the same functional role can be realized by a diversity of structures, and because natural selection encourages this diversity, the full macromolecular explanation for (PS) or for (G) will have to advert to a range of physical systems that realize independent assortment in many different ways. These different ways will be an unmanageable disjunction of alternatives so great that we will not be able to recognize what they... 

Besides its problems in undermining putative macromolecular explanations of (PS), (G) and what (G) explains, antireductionism faces some problems in substantiating its claims that (PS) explains (G) and (G) explains individual cases of genetic recombination. The problems, of course, stem from the fact that neither (PS) nor (G) are laws, and therefore an account is owing of how statements like these can explain. This, in fact, is a problem that any revision of a thesis of reductionism must come to grips with as well. So, perhaps we should turn to this problem directly, and then reformulate and reassess both reductionism and antireductionism as explanatory theses in its light. 

For many years, it was thought that the macro solute forms a new phase near the membrane—that of a gel or gel-like layer. The model provided good correlations of experimental data and has been widely used. It does not fit known experimental facts. An explanation that fits the known data well is based on osmotic pressure. The van t Hoff equation [Eq. (22-75)] is hopelessly inadequate to predict the osmotic pressure of a macromolecular solution. Using the empirical expression... 

Antireductionists wedded to alternative, non-erotetic accounts of explanation, cannot adopt the gambit of a Protagorian theory of explanation in any case. They will need a different argument for the claim that neither (G) nor (PS) can be explained by its macromolecular supervenience base, and for the claim that (PS) does explain (G), and (G) does explain individual cases of recombination. One argument such antireductionists might offer for the... 

Antireductionists will differ from reductionists, not on the facts, but on whether the initial explanation was merely an incomplete one or just a how-possibly explanation. Antireductionists will agree that the macromolecular genetic and biochemical pathways are causally necessary to the truth of the purely functional ultimate explanation. However, they don t complete an otherwise incomplete explanation. They are merely further facets of [the] situation that molecular research might illuminate (Kitcher, 1999, p. 199). The original ultimate answer to the question as to why do butterflies have eyespots does provide a complete explanatory answer to a question. Accordingly, how-possibly explanations are perfectly acceptable ones, or else the ultimate explanation in question is something more than a mere how-possibly explanation. 

This impossibility of reducing a complex process to single macromolecules explains the co-existence of different levels of explanation in biologists molecular descriptions. This does not mean that the nature of the molecular components is of no importance, nor that the complex functions originate only from the rules of assembly of the different macromolecular components. The organization of living beings is based both on the precise nature of the molecular components and on the way that these molecular components are assembled. 

Mark s x-ray work on fibrous macromolecular substances began in 1925, with his publication, together with Katz, of a paper on cellulose. He continued the work on cellulose with Meyer and Susich (1929). In 1926 he and Hauser published a report of their studies of rubber. He had developed excellent ideas about the nature of rubber and the explanation of its extensibility and elasticity. I remember that when I visited him in Ludwigshafen in the summer of 1930 both he and I took... 

Table 18. Values173) of (molecular weight x 10-4) for two polystyrene samples PS - PX prepared by Asahi Dow Chem. Co. Ltd. and PS - IU distributed by Macromolecular Division of I.U.P.A.C. see footnote for further details and explanation of abbreviations...

Gordon RJ (1970) On the explanations and correlations of turbulent drag reduction in dilute macromolecular solutions J Appl Polym Sci 14 2097... 

Fig. 4.7. Ligands may still bind to a receptor after covalent modification with a photoaffinity reagent. Here a receptor (unshaded) is labeled with a macromolecular reagent (hatched) made by attaching a bifunctional reagent to a natural ligand (stipled). For an explanation see...

In those instances in which all categories of macromolecular biosyntheses fail entirely61), the explanation can be sought either in effects on the bacterial membrane or in a failure of energy generation or transduction. 

In some of the first studies connected with the discovery of the general phenomenon of cocatalysis, f-butanol was found to play such a role in the polymerisation of isobutene by boron fluoride There is an apparent contradiction between this observation and tire fact that polyisobutene chains bearing hydroxyl end groups , i.e. the same structure as f-butanol, do not exhibit a cocatalytic function (see all the evidence of limited yields due to water consumption by termination with counterion to give those end groups). The likely explanation of this dichotomy is that the OH groups on the polymer molecules are embedded in the macromolecular cofls and therefore much less reactive towards the Lewis acid-moncaner complex. 

The most reasonable explanation for the increase in apparent hydrodynamic diameter measured by DLS is the enhanced micelle-micelle interactions as the boundary of a two-phase system is approached (i.e., the pressure is lowered). Figure 4 illustrates this concept of micelle-micelle interactions, which is manifested as aggregation (or clustering) of the reverse micelle or microemulsion droplets. Since the solvent environment is essentially unchanged by this "macromolecular aggregation" (Ui) we exclude the possibility of (other than transitory) micelle-micelle coalescence to form stable, larger micelles. The micelles may coalesce briefly to form transitional species (which might be a "dumbbell" or more cylindrical structures), in which the water cores collide and intermix. 

Evidence continues to support the explanation of en/.yme catalysis on the basis of the active site (reactive center) of amino acid residues, which is considered to be that relatively small region of the en/yme s macromolecular surface involved in catalysis. Within this site, the enzyme has. strategically positioned functional groups (frnm the side chains of amino acid units) that participate cooperatively in the catalytic action." ... 

In a recent NMR study, Derenne et al.(77) obtained evidence for non hydrolyzable amide structures in refractory fractions of the algae Scenedesmus quadricauda. The solid-state NMR spectra showed a major peak around -260 ppm for amides accompanied by a peak around -195 ppm for substituted pyrroles and a shoulder at -235 ppm assigned to unsubstituted pyrroles of the insoluble residue. The authors suggest, that the amides are protected by association with long polymethylenic chains within a macromolecular network. Knicker and Hatcher offer an alternative explanation,- that protection of amide functional groups as part of proteinaceous material are affected by encapsulation within the macromolecular matrix forming sedimentaryhumic material(7.. ... 

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