C-value paradox

DNA. This discrepancy between genome size and genome complexity is called the C-value paradox. 

C-value paradox. The observation that organismal complexity is not always directly related to genome size because of differences in the amount of repetitive DNA. 

Cavalier-Smith, T. (1978) Nuclear volume control by nudeoskeletal DNA, selection for cell volume and cell growth rate, and the solution of the DNA C-value paradox. Journal of Cell Science, Vol.34,247-278... 

Product studies show (i) that the ease of elimination of Rp from R1R2R3COH depends on the relative stabilities of Rp, R2 and R3- and (//) that Rp can be eliminated from RjRjHCOH, i.e. that secondary alcohols can undergo a measure of C-C fission via an alkoxyl radical. The extent of C-C fission increases when RjRjDCOH is employed, but the h/ d values for several alcohols do not accord with the observed products . This paradox has been discussed at length . 

C kinetic isotope effects (A ( C)/ ( C)) are more difficult to measure accurately. The values for a variety of metal ion-catalyzed decarboxylations of oxaloacetate (2.113) are similar (1.04-1.05). This suggests that the transition state for decarboxylation (a) involves a marked breakage of the C — C bond and (b) is similar for the various metal ions, even though enhancement rates vary widely. This apparent paradox is ascribed to an alteration of the distribution of oxaloacetate between the keto and enol forms. ... 

Because n > n2, for values of i greater than c, the combination of (9.11) and (9.12) produces the seemingly paradoxical result sin 2 > 1 . This result can be accepted because the electric vector is a complex number and because an electromagnetic wave does not propagate in medium ri but only penetrates into it. The standing wave at the interface then forms an evanescent field at the n2 side of the interface. 

We now seek a solution of (9 7) and (9-8) for small values of the Peclet number, Pe , by using the matched asymptotic expansion procedure that was detailed for uniform flow past a sphere in Section C. Although the reader may not immediately see that the derivation of an asymptotic solution for this new problem necessitates use of the matched asymptotic expansion technique, an attempt to develop a regular expansion for 9 for Pe 1 leads to a Whitehead-type paradox similar to that encountered for the uniform-flow problem. 

As a consequence of the temperature dependence of A/ftf and ASjj, AGn(D shows a bell-shaped curve an example is given in Fig. 2. This has two important implications (1) AG CT), which measures the stability of the protein, passes through a maximum at a temperature Fmax, usually in the 0-50°C range, at which the native conformation is stabilized only by the enthalpy difference between the two states. As already stressed in the introduction, AGN(Fmax) is rather small, albeit it results from comparatively large enthalpic and entropic effects typical values are of the order of 50 kJ per mole of protein. (2) On both sides of Fmax, stability decreases and there are two temperatures at which AG becomes zero, i.e., denaturation occurs the upper one corresponds to the temperature of the usual heat denaturation process, the lower one to the somewhat paradoxical process of cold denaturation the paradox lies in that cold denaturation is an exother-... 

In the presence of a thiol, the OH-adduct can be reduced, the reducing C(5)-OH-C(6)-yl radical, paradoxically, apparently more readily than the oxidizing C(6)-OH-C(5)-yl one. Nevertheless, the rate of this reaction must be very slow, as in the radiolysis of N20-saturated solution of 5 -thymidylic acid in the presence of 5% cysteamine, thioethers Le. the recombination products of a cysteamine-derived thiyl radical with a 5 -thymidylic-acid-derived OH-adduct radical, are formed with a G value as high as 1.5 X 10 mol J [35] in a competitive reaction [36]. 

An important, but subtle, factor influencing the B-values of the MAX phases is their stoichiometry, and more specifically their vacancy concentrations. This effect is best seen in the B-values of Ti2AlN, where theory and experiment show a decrease in lattice parameters as C is substituted for by N. Given that the lattice parameters shrink, it is not surprising that theory predicts that this substitution should increase the B-value, when, in fact, experimentally it decreases with increasing N-content [42]. This paradox is resolved when it is appreciated that B is a strong function of vacancies, and that the addition of N results in the formation of vacancies on the A1 and/or N sites. As discussed below, the presence of these defects also influence other properties [43, 44]. 

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