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Results for “Biological Evolution”

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At least 19 recordsLinked to original sources
PubMed1980

The evolution of the protein synthesis system, II. From chemical evolution to biological evolution.

The sequence of events previously proposed for modern protein synthesis is reviewed. It begins with an abiological synthesis of a template, and evolves through two model autocatalytic systems to a primitive cell that has a rudimentary biological protein synthesis system. A possible scheme for the origin of tRNA's is described so as to fill the gap between the model and the modern system. Fragments of genes that existed in and around the primitive system are proposed to be precursors of tRNA's. Since these fragments must have been undesirable components for the system, the origin and evolution of tRNA's may be regarded as an excellent answer by the primitive system to adverse circumstances.

Animals↗
PubMed2003

The human genome and comparative genomics: understanding human evolution, biology, and medicine.

The entire 2.9-billion-letter sequence (nucleotide base pairs) of the human genome is available as a resource for scientific discovery. Some of the findings from the completion of the human genome were expected, confirming knowledge anticipated by many years of research and analysis in both human and comparative genetics. Other findings were not expected. In either case, the availability of the human genome is likely to have significant implications on basic research, clinical investigation, and ultimately the practice of medicine.

Biological Evolution↗
PubMedDate not supplied

[Thermodynamic theory of biological evolution and aging. Experimental verification of the theory].

Experimental data confirming original thermodynamic theory of biological evolution and aging are presented. Biological evolution (phylogenesis) and ontogenesis can be easily described within the frames of equilibrium hierarchical thermodynamics on the basis of temporal hierarchies law and the second principle of thermodynamics. The theory explains many facts and suggests new practical proposals in medical and biological science, particularly, in dietology, gerontology, and geriatrics. Application of the temporal hierarchies model to studying living nature offers horizonless possibilities for its understanding.

Aging↗
PubMed2003

[Biological evolution and specialization].

There were some disputes about the concept and mechanism of biological evolution. This paper tried to give more explanations on the key concepts. The biological adaptability was distinguished into two different concepts: biological evolution and specialization. The former was defined as the process of biologically gradual evolvement, and the latter was considered as the process of species formation at horizontal development. Moreover, a new conceptual framework was applied to the popular biological theories known by people, and the previous research results or discoveries were explained over again.

Animals↗
PubMed2003

Protein aggregation and aggregate toxicity: new insights into protein folding, misfolding diseases and biological evolution.

The deposition of proteins in the form of amyloid fibrils and plaques is the characteristic feature of more than 20 degenerative conditions affecting either the central nervous system or a variety of peripheral tissues. As these conditions include Alzheimer's, Parkinson's and the prion diseases, several forms of fatal systemic amyloidosis, and at least one condition associated with medical intervention (haemodialysis), they are of enormous importance in the context of present-day human health and welfare. Much remains to be learned about the mechanism by which the proteins associated with these diseases aggregate and form amyloid structures, and how the latter affect the functions of the organs with which they are associated. A great deal of information concerning these diseases has emerged, however, during the past 5 years, much of it causing a number of fundamental assumptions about the amyloid diseases to be re-examined. For example, it is now apparent that the ability to form amyloid structures is not an unusual feature of the small number of proteins associated with these diseases but is instead a general property of polypeptide chains. It has also been found recently that aggregates of proteins not associated with amyloid diseases can impair the ability of cells to function to a similar extent as aggregates of proteins linked with specific neurodegenerative conditions. Moreover, the mature amyloid fibrils or plaques appear to be substantially less toxic than the pre-fibrillar aggregates that are their precursors. The toxicity of these early aggregates appears to result from an intrinsic ability to impair fundamental cellular processes by interacting with cellular membranes, causing oxidative stress and increases in free Ca2+ that eventually lead to apoptotic or necrotic cell death. The 'new view' of these diseases also suggests that other degenerative conditions could have similar underlying origins to those of the amyloidoses. In addition, cellular protection mechanisms, such as molecular chaperones and the protein degradation machinery, appear to be crucial in the prevention of disease in normally functioning living organisms. It also suggests some intriguing new factors that could be of great significance in the evolution of biological molecules and the mechanisms that regulate their behaviour.

Amyloid↗
PubMedDate not supplied

[The thermodynamic direction of biological evolution. The model and the reality].

A macrothermodynamic model of evolution of the supramolecular structures and chemical composition of living objects during ontogenesis and at long-term stages of general biological evolution is presented. A study of quasiclosed (thermodynamically and kinetically) systems, phases of the biomass supramolecular structures, enables a conclusion on the thermodynamic direction of biological evolution to be made. In correspondence with the second principle, this direction leads to variations in the chemical composition and structure of the living systems during their development. Indirect and direct evidence of the trend to a minimal Gibbs specific function of formation of the supramolecular structures in animal tissues during ontogenesis are presented. The conclusion that thermodynamics is the "driving force" of evolution of the biological world is confirmed.

Animals↗
PubMed1982

A mathematical model of biological evolution.

In order to understand generally how the biological evolution rate depends on relevant parameters such as mutation rate, intensity of selection pressure and its persistence time, the following mathematical model is proposed: dNn(t)/dt = (mn(t) - mu)Nn(t) + muNn-1(t) (n = 0,1,2,3,...), where Nn(t) and mn(t) are respectively the number and Malthusian parameter of replicons with step number n in a population at time t and mean is the mutation rate, assumed to be a positive constant. The step number of each replicon is defined as either equal to or larger by one than that of its parent, the latter case occurring when and only when mutation has taken place. The average evolution rate defined by v infinity identical to lim t leads to infinity sigma infinity n = o nNn(t)/t sigma infinity n = o Nn(t) is rigorously obtained for the case (i) mn(t) = mn is independent of t (constant fitness model), where mn is essentially periodic with respect to n, and for the case (ii) mn(t) = s(-1) n+[t/tau] (periodic fitness model), together with the long time average -m infinity of the average Malthusian parameter -m identical to sigma infinity n = o mn(t)Nn(t)/sigma infinity n = o Nn(t). The biological meaning of the results is discussed, comparing them with the features of actual molecular evolution and with some results of computer simulation of the model for finite populations.

Animals↗
PubMedDate not supplied

[The dynamic trends of biological evolution].

The available data on the thermodynamic stability of supramolecular biological structures and variations in the chemical composition of living organisms have allowed a macrothermodynamic model of biological evolution to be developed experimentally. In this model, the tendency toward a minimum of the specific Gibbs function of the formation of supramolecular structures of living organisms causes variations in the chemical composition and structure of living systems. It is shown that in the course of ontogenesis and phylogenesis, as well as long-lasting stages in the evolution of the organic world, the biosystems (as a result of the thermodynamic direction of evolutionary processes of the formation of supramolecular structures) are enriched with energy-intensive chemical substances, which displace water from these biosystems. The change in the composition and structure of biostructures of an adaptive character is also explained from the angle of macrothermodynamics.

Animals↗
PubMed2004

The modern theory of biological evolution: an expanded synthesis.

In 1858, two naturalists, Charles Darwin and Alfred Russel Wallace, independently proposed natural selection as the basic mechanism responsible for the origin of new phenotypic variants and, ultimately, new species. A large body of evidence for this hypothesis was published in Darwin's Origin of Species one year later, the appearance of which provoked other leading scientists like August Weismann to adopt and amplify Darwin's perspective. Weismann's neo-Darwinian theory of evolution was further elaborated, most notably in a series of books by Theodosius Dobzhansky, Ernst Mayr, Julian Huxley and others. In this article we first summarize the history of life on Earth and provide recent evidence demonstrating that Darwin's dilemma (the apparent missing Precambrian record of life) has been resolved. Next, the historical development and structure of the "modern synthesis" is described within the context of the following topics: paleobiology and rates of evolution, mass extinctions and species selection, macroevolution and punctuated equilibrium, sexual reproduction and recombination, sexual selection and altruism, endosymbiosis and eukaryotic cell evolution, evolutionary developmental biology, phenotypic plasticity, epigenetic inheritance and molecular evolution, experimental bacterial evolution, and computer simulations (in silico evolution of digital organisms). In addition, we discuss the expansion of the modern synthesis, embracing all branches of scientific disciplines. It is concluded that the basic tenets of the synthetic theory have survived, but in modified form. These sub-theories require continued elaboration, particularly in light of molecular biology, to answer open-ended questions concerning the mechanisms of evolution in all five kingdoms of life.

Animals↗