Explanation molecular

Give a molecular explanation for the following trend in alcohol solubilities in water ... 

The reason is simple. If the aim of science is explanation and explanations in functional biology are adequate, complete, and correct, then the methodological prescription that we must search for molecular completions, corrections, or foundations of these functional explanations in molecular processes, will be unwarranted. Consequently, molecular biology need not be the inevitable foundation for every compartment of functional biology. If the aim of science is explanation, and functional explanations are either false or incomplete, and molecular explanations either (more) correct or (more) complete, then biology must act on the methodological prescription... 

Leave aside for the moment the claim that (PS) is a full explanation of (G), and consider why, according to the antireductionist, no molecular explanation of (PS) is possible. 

Finally, in this last group, we include lead that causes saturnism7, particularly among young children in socially deprived inner cities. The toxicity of environmental Pb finds its molecular explanation in the extraordinary high affinity of Pb (binding constant of 1015 M) for the key Zn-dependent enzyme of haem biosynthesis, porphobilinogen synthase. 

Additional rings on paromomycin and gentamicin Cla point to a molecular explanation of why 4, 6 -disubstituted aminoglycosides are more specific for the A-site binding pocket and enhance the affinity of aminoglycosides for the decoding site. 

These genetic diseases are examples of the various molecular explanations for dominant inheritance. 

The mode of action of sulfanilamides became known around 1947, when the structure and biosynthesis of folic acid were elucidated. This compound is built by bacteria from the heterocyclic pteroyl moiety, p-aminobenzoate, and glutamate. p-Aminobenzene-sulfonamide (9.89, sulfanilamide) is a competitive inhibitor of the synthase enzyme, acting as an antimetabolite of p-aminobenzoate. Occasionally, the sulfanilamide can even be incorporated into the modified folate, resulting in an inactive compound and thus an inactive enzyme. This theory, proposed by Woods and Fildes in 1940, became the first molecular explanation of drug action. 

Because of the scarcity of data in other types of deformation than unilateral extension, the variability of Cx and C2 with the type of strain has escaped the attention of several authors involved in molecular explanations of the C2 term. Quite recently Bobear (15) and in greater detail Blokland (14) have given this matter further consideration. We will return to Blokland s work in Chapter IV, Section 3. 

Ordered mechanisms often occur in the reactions of the NAD+-linked dehydrogenases, with the coenzyme binding first. The molecular explanation for this is that the binding of the dinucleotide causes a conformational change that increases the affinity of the enzyme for the other substrate (see Chapter 16). 

It should be added that no experimental evidence exists providing a molecular explanation for the requirements and role of the aromatic hydroxyl(s). Descriptively, it is clear that a hydroxyl "meta" to an aminoethyl fragment is important, but almost nothing is known about the cause of this "meta effect". Only the recent demonstration that this effect is chirally modulated 1 ) suggests that factors extrinsic to the drug (i.e., specific drug-receptor interactions), rather than purely intrinsic factors (e.q., 0-N distance or drug dipoles), may be responsible. 

Gold and Grist (1972) concluded that strongly basic anions perturb the water molecules that are hydrogen bonded to them, thereby contributing to inverse solvent kinetic isotope effects, but they did not provide evidence for a molecular explanation. 

The 5 sequence is not essential for accurate transcription initiation. When the region extending from the 5 end of the gene (that is, the part that would normally be considered to be the promoter) is deleted, RNA synthesis is carried out just as efficiently as on the native gene. The new 5 end of the transcript is complementary to whatever sequences take the place of the natural ones. Furthermore, initiation is only affected when sequences within the 5S rRNAgene are disrupted. The molecular explanation for this phenomenon is as follows ... 

The above explanation is just a sketchy overview of the biochemistry of vision. Ultimately, though, this is the level of explanation for which biological science must aim. In order to truly understand a function, one must understand in detail every relevant step in the process. The relevant steps in biological processes occur ultimately at the molecular level, so a satisfactory explanation of a biological phenomenon—such as sight, digestion, or immunity—must include its molecular explanation. 

An attempt to make this application prompted the appearance of The Thermodynamics of Soil Solutions (Oxford University Press, 1981). Besides its evident purpose, to demonstrate the use of chemical thermodynamics, this book carried a leitmotif on the fundamental limitations of chemical thermodynamics for describing natural soils. These limitations referred especially to the influence of kinetics on stability, to the accuracy of thermodynamic data, and to the impossibility of deducing molecular mechanisms. The problem of mechanisms vis-a-vis thermodynamics cannot be expressed better than in the words of M. L. McGlashan 2 what can we learn from thermodynamic equations about the microscopic or molecular explanation of macroscopic changes Nothing whatever. What is a thermodynamic theory (The phrase is used in the titles of many papers published in reputable chemical journals.) There is no such thing. What then is the use of thermodynamic equations to the chemist They are indeed useful, but only by virtue of their use for the calculation of some desired quantity which has not been measured, or which is difficult to measure, from others which have been measured, or which are easier to measure. This point cannot be stated often enough. 

Molecular explanation of the tendency to contract. The simplest properties of molecules in liquids suffice to account for this tendency of the surfaces to contract. Molecules are small objects, possessing definite size and shape, in all states of matter in all fluids they are free to move relative to one another, and in liquids they are kept close to each other, by the cohesions forces between them. Liquids are thus distinguished from solids by their fluidity, that is, the freedom of the molecules to move and from gases by the fact that the attraction between the molecules restrains the motions sufficiently to prevent more than a small... 

Fig. 5. A multipathway mechanism of action for insulin. Insulin exerts a plethora of actions on target tissues and it is extremely difficult to visualize a single second message acting to achieve all such effects. Here it is suggested that a number of signals emanate from the plasma membrane as a consequence of insulin binding to its receptor. This may also offer a molecular explanation for selective insulin-resistant states noted in type-1 and type-II human diabetes as well as experimentally in animals. In such circumstances lesions could occur at particular points on this multipathway .

Italian chemist and physicist Amadeo Avogadro (1776-1856) proposed a correct molecular explanation for Gay-Lussac s law of combining volumes. His work provided a simple way to determine atomic weights and molecular weights of gases. 

Although a vast majority of important chemical reactions occur primarily in liquid solution, the study of simple gas-phase reactions is very important in developing a theoretical understanding of chemical kinetics. A detailed molecular explanation of rate processes in liquid solution is extremely difficult. At the present time reaction mechanisms are much better understood for gas-phase reactions even so this problem is by no means simple. This experiment will deal with the unimolecular decomposition of an organic compound in the vapor state. The compound suggested for study is cyelopentene or di-i-butyl peroxide, but several other compounds are also suitable see, for example. Table XI.4 of Ref. 1. 

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