首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 0 毫秒
1.
To the extent that all biological phenomena are perceivable only through their physical manifestations, it may be justified to assume that all biological phenomena will be eventually represented in terms of physics; perhaps not of present day physics, but of some “extended” form of it. However, even if this should be correct, it must be kept in mind that representing individual biological phenomena in terms of physics is not the same as deducing from known physical laws the necessity of biological phenomena. Drawing an analogy from pure mathematics, it is possible that while every biological phenomenon may be represented in terms of physics, yet biological statements represent a class of “undecidable” statements within the framework of physics. Such a conjecture is reinforced by the history of physics itself and illustrated on several examples. The 19th century physicists tried in vain todeduce electromagnetic phenomena from mechanical ones. A similar situation may exist in regard to biological and social sciences. Quite generally, the possibility of representing a class B phenomena in terms of class A phenomena does not imply that the phenomena of class B can be deduced from those of class A. The consequences of the above on the relation between physics, biology, and sociology are studied. A tentative postulational formulation of basic biological principles are given and some consequences are discussed. It is pointed out that not only can the study of biological phenomena throw light on some physical phenomena, but that the study of social phenomena may be of value for the understanding of the structures and functions of living organisms. The possibility of a sort of “socionics” is indicated.  相似文献   

2.
The theory of organismic sets, introduced by N. Rashevsky (Bulletin of Mathematical Biophysics,29, 139–152, 1967;30, 163–174, 1968), is developed further. As has been pointed out, a society is a set of individuals plus the products of their activities, which result in their interactions. A multicellular organism is a set of cells plus the products of their activities, while a unicellular organism is a set of genes plus the products of their activities. It is now pointed out that a physical system is a set of elementary particles plus the product of their activities, such as transitions from one energy level to another. Therefore physical, biological and sociological phenomena can be considered from a unified set-theoretical point of view. The notion of a “world set” is introduced. It consists of the union of physical and of organismic sets. In physical sets the formation of different structure is governed preponderantly by analytical functions, which are special type of relations. In organismic sets, which represent biological organisms and societies, the formation of various structures is governed preponderantly by requirements that some relations, which are not functions, be satisfied. This is called the postulate of relational forces. Inasmuch as every function is a relation (F-relation) but not every relation is a function (Q-relation), it has been shown previously (Rashevsky,Bulletin of Mathematical Biophysics,29, 643–648, 1967) that the physical forces are only a special kind of relational force and that, therefore, the postulate of relational forces applies equally to physics, biology and sociology. By developing the earlier theory of organismic sets, we deduce the following conclusions: 1) A cell in which the genes are completely specialized, as is implied by the “one gene—one enzyme” principle, cannot be formed spontaneously. 2) By introducing the notion of organismic sets of different orders so that the elements of an organismic set of ordern are themselves organismic sets of order (n−1), we prove that in multicellular organisms no cell can be specialized completely; it performs, in addition to its special functions, also a number of others performed by other cells. 3) A differentiated multicellular organism cannot form spontaneously. It can only develop from simpler, less differentiated organisms. The same holds about societies. Highly specialized contemporary societies cannot appear spontaneously; they gradually develop from primitive, non-specialized societies. 4) In a multicellular organism a specialization of a cell is practically irreversible. 5) Every organismic set of ordern>1, that is, a multicellular organism as well as a society, is mortal. Civilizations die, and others may come in their place. 6) Barring special inhibitory conditions, all organisms multiply. 7) In cells there must exist specially-regulatory genes besides the so-called structural genes. 8) In basically identically-built organisms, but which are built from different material (proteins), a substitution of a part of one organism for the homologous part of another impairs the normal functioning (protein specificity of different species). 9) Even unicellular organisms show sexual differentiation and polarization. 10) Symbiotic and parasitic phenomena are included in the theory of organismic sets. Finally some general speculations are made in regard to the possibility of discovering laws of physics by pure mathematical reasoning, something in which Einstein has expressed explicit faith. From the above theory, such a thing appears to be possible. Also the idea of Poincaré, that the laws of physics as we perceive them are largely due to our psychobiological structure, is discussed.  相似文献   

3.
A hypothetical “self-reproducing living molecule” has been recently frequently discussed in the literature. A physical theory of such a molecule is tentatively outlined. The relational, rather than the quantitative, aspects of the process are emphasized. The process of synthesis of such a molecule from its components is considered as a transition of a complex system between two quantum-mechanical states. The requirement that a “living molecule” should be able to multiply only by self-reproduction but not by a formationde novo leads to the conclusion that the above mentioned transition is a forbidden one. A constellation of conditions under which the forbiddenness is lifted by the presence of an already existing “living molecule” is suggested. The outlined mechanism leads to the conclusion that the property of self-reproduction does not so much reside in the self-reproducing molecule itself as in its relations to other molecules of a system.  相似文献   

4.
The author's suggestion that the behavior of an individual or of a society may be described not by maximizing the satisfaction function but by maximizing the integral of it over a period of time (Rashevsky,Mathematical Biology of Social Behavior, rev. ed., p. 233, Chicago: The University of Chicago Press) has been considered applicable to other biological functions in a recent paper by R. Rosen (Bull. Math. Biophysics,24, 279–290, 1962). It is pointed out that the possibility of introducing such variational principles into biology or sociology requires that the corresponding functions depend explicitly and in a nonlinear manner on the rate of change of some of the variables. An example of a satisfaction function is given that describes the behavior of an individual who derives more satisfaction from the process of approaching a goal than from the actual goal itself.  相似文献   

5.
6.
Under certain assumptions concerning the probabilities of “mutations,” i.e. changes of structure of bird societies, it is shown that the probability distribution for all possible structures of a society ofN individuals approaches a limit independent of the initial probability distribution. A formula for the limiting distribution is derived.  相似文献   

7.
We summarise the contributions to the discussion and the links between them. The complex relationship between the physical and biological sciences demonstrates three "axes of tension": the role of simulation, the interplay between levels of explanation, and the generality of "laws". We identify examples of true synergy between approaches that genuinely explore new research territory, and underscore the contemporary value of the type of discussions contained in this volume.  相似文献   

8.
Oligo(2'-O-alkylribonucleotides) have been synthesized in which alkyl is methyl, allyl and butyl. The various phosphoramidite monomers of 2'-O-alkyl uridine, cytidine, adenosine, guanosine, inosine and 2,6-diaminopurine riboside have been synthesized from a minimum of key intermediates. Extra protection of the lactam function in uracil and hypoxanthine proves useful. The high stability of the oligomers combined with incorporation of non-radioactive reporter groups such as fluorophores, biotin and 2,4-dinitrophenylamino (DNP) moities renders them as excellent antisense tools for studying RNA processing, for locating and visualising RNA and RNP complexes in cells, for examining splicing complexes by electron microscopy and for the affinity chromatography of RNA or RNP complexes.  相似文献   

9.
10.
Morphogenesis takes place against a background of organism-to-organism and environmental variation. Therefore, fundamental questions in the study of morphogenesis include: How are the mechanical processes of tissue movement and deformation affected by that variability, and in turn, how do the mechanic of the system modulate phenotypic variation? We highlight a few key factors, including environmental temperature, embryo size and environmental chemistry that might perturb the mechanics of morphogenesis in natural populations. Then we discuss several ways in which mechanics-including feedback from mechanical cues-might influence intra-specific variation in morphogenesis. To understand morphogenesis it will be necessary to consider whole-organism, environment and evolutionary scales because these larger scales present the challenges that developmental mechanisms have evolved to cope with. Studying the variation organisms express and the variation organisms experience will aid in deciphering the causes of birth defects.  相似文献   

11.
12.
合成生物学是一个新兴而极具研究前景的领域.旨在通过将多种天然或人工设计的生物学元件进行合理组合,创造出重构的或非天然的生物系统。综述了合成生物学这一新兴学科的核心理念、研究内容以及与相关学科的联系,详细介绍了J.CraigVenter研究小组所合成的“人造生命”,并展望了合成生物学广阔的发展前景和所面临的问题。  相似文献   

13.
The principles of bone biology and physiology permeate all subspecialty practices in plastic and reconstructive surgery, from hand surgery to aesthetic surgery. Despite its importance in our practices, these topics rarely surface within textbooks, literature reviews, or residency curricula. The authors present the second portion of a two-part review of the important concepts of bone biology and bone physiology relevant to plastic surgery, in an effort to ameliorate this educational gap.  相似文献   

14.
Mathematical biology has hitherto emphasized the quantitative, metric aspects of the physical manifestations of life, but has neglected the relational or positional aspects, which are of paramount importance in biology. Although, for example, the processes of locomotion, ingestion, and digestion in a human are much more complex than in a protozoan, the general relations between these processes are the same in all organisms. To a set of very complicated digestive functions of a higher animal there correspond a few simple functions in a protozoan. In other words, the more complicated processes in higher organisms can be mapped on the simpler corresponding processes in the lower ones. If any scientific study of this aspect of biology is to be possible at all, there must exist some regularity in such mappings. We are, therefore, led to the following principle: If the relations between various biological functions of an organism are represented geometrically in an appropriate topological space or by an appropriate topological complex, then the spaces or complexes representing different organisms must be obtainable by a proper transformation from one or very fewprimordial spaces or complexes. The appropriate representation of the relations between the different biological functions of an organism appears to be a one-dimensional complex, or graph, which represents the “organization chart” of the organism. The problem then is to find a proper transformation which derives from this graph the graphs of all possible higher organisms. Both a primordial graph and a transformation are suggested and discussed. Theorems are derived which show that the basic principle of mapping and the transformation have a predictive value and are verifiable experimentally. These considerations are extended to relations within animal and human societies and thus indicate the reason for the similarities between some aspects of societies and organisms. It is finally suggested that the relation between physics and biology may lie on a different plane from the one hitherto considered. While physical phenomena are the manifestations of the metric properties of the four-dimensional universe, biological phenomena may perhaps reflect some local topological properties of that universe.  相似文献   

15.
16.
Bohr, Delbrück and Schrödinger were physicists who had important influences on biology in the second half of the twentieth century. They thought that future studies of the gene might reveal new principles or paradoxes, analogous to the wave/particle paradox of light propagation, or even new physical laws. This stimulated several physicists to enter the field of biology. Delbrück founded the bacteriophage group which provided one of the roots of molecular biology. Another was X-ray crystallography which led to the discovery of DNA structure. The strength and success of molecular biology came from the many interactions between geneticists, physicists, chemists and biochemists. It was also characterized by a powerful combination of theoretical and experimental approaches.  相似文献   

17.
Linear and cyclic analogues of cyclolinopeptide A (CLA) with two dipeptide segments (Val(5)-Pro(6) and Pro(6)-Pro(7)) replaced by their tetrazole derivatives were synthesized by the SPPS technique and cyclized using TBTU (O-(benzotriazol-1-yl)-1,1,3,3-tetramethyluronium tetrafluoroborate) reagent. The conformational properties of the c(Leu(1)-Ile(2)-Ile(3)-Leu(4)-Val(5)-Pro(6)-psi[CN(4)]-Ala(7)-Phe(8)-Phe(9)) were investigated by NMR and computational techniques. The overall solution structure of this cyclic peptide resembles that observed for the CLA in the solid state. These studies of cyclic tetrazole CLA analogue confirm that the 1,5-disubstituted tetrazole ring functions as an effective, well-tolerated cis-amide bond mimic in solution. The peptides were examined for their immunosuppressive activity in the humoral response test. For cyclic analogues the immunosuppressive activity, at low doses, is equal in magnitude to the activity presented by cyclosporin A and native CLA. The conformational and biological data seem indicate that the Pro-Pro-Phe-Phe moiety and the preservation of the CLA backbone conformation are important for immunosuppressive activity.  相似文献   

18.
芳香类天然产物的合成生物学研究进展   总被引:1,自引:0,他引:1  
植物芳香类天然产物具有重要的药用价值,可制成具有抗菌、抗炎、镇痛、抗氧化、杀虫驱虫、祛痰止咳、安神镇静和抗肿瘤等药效的医药保健用品.然而,由于植物中芳香类天然产物含量较低并且难以提取和纯化,严重限制了其工业化生产及应用.合成生物学和代谢工程技术的发展为天然产物的生产提供了新的思路,可以利用人工微生物细胞工厂来实现多种芳...  相似文献   

19.
20.
Summary This paper follows on from Part 1 of my review of bromodeoxyuridine published earlier this year (Dolbeare, 1995).  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号