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Chromosome theory

Thomas H. Morgan Physiology/Medicine Chromosome theory and chromosome maps... [Pg.83]

In 1902, Walter Sutton and Theodor Boveri were able to show that the Mendelian characters (the genes) are physically carried by chromosomes (the chromosome theory of heredity), and the study of meiotic divisions and gametogenesis proved that Mendel s hypotheses were absolutely correct, so much so that they could be regarded no longer as hypotheses but as experimental realities. Mendel s laws gave a direct support to the conclusions that Darwin had obtained from the breeders. Every individual is indeed unique, because the recombination of its genes is a totally random process. [Pg.49]

The rediscovery of Mendel s laws, the demonstration of crossing-over, the chromosome theory of heredity, the link between sex and XX or XY chromosomes, and the discovery of the first Mendelian disorders in man (alcaptonuria and brachydactyly) were all obtained in the first ten years of the twentieth century. In that brief period of time, light was thrown on the millennial mystery of heredity, and genetics became a science. [Pg.51]

Bridges C.B. 1916. Non-disjunction as proof of the chromosome theory of heredity. Genetics 1 1-52. [Pg.84]

In the style of the Darwinian Theory, the quality of a chromosome is called its fitness. The quality or fitness of a ehromosome is usually caleulated with the help of an objeetive function, which is a mathematical function indicating how good the solution, and thus the chromosome, is for the optimization problem. This computation of the fitness is done for each chromosome in each population,... [Pg.469]

ITowever, most normal somatic cells lack telomerase. Consequently, upon every cycle of cell division when the cell replicates its DNA, about 50-nucleotide portions are lost from the end of each telomere. Thus, over time, the telomeres of somatic cells in animals become shorter and shorter, eventually leading to chromosome instability and cell death. This phenomenon has led some scientists to espouse a telomere theory of aging that implicates telomere shortening as the principal factor in cell, tissue, and even organism aging. Interestingly, cancer cells appear immortal because they continue to reproduce indefinitely. A survey of 20 different tumor types by Geron Corporation of Menlo Park, California, revealed that all contained telomerase activity. [Pg.382]

Revell, S.H. (1974). The breakage-and-reunion theory and the exchange theory for chromosome aberrations induced by ionizing radiations A short history. In Advances in Radiation Biology (Lett, J.T. and Zelle, M., Eds.). Vol. 4, Academic Press, New York, pp. 367-415. [Pg.234]

As indicated above in the section on "Genotoxic Effects", it is likely that mirex and chlordecone are tumor promoters and not tumor initiators. Initiators irreversibly alter DNA by a mutation, chromosomal aberration, or other alteration. Promoters act by facilitating the proliferation of previously initiated preneoplastic cells. One of the mechanisms for promotion is believed to involve suppression of inhibitory proliferative control through inhibition of gap-junctional-mediated intercellular communication as well as enzyme induction (Trosko et al. 1983). The results of studies to evaluate the promotional activity potential of mirex in mice indicate that mirex is a mouse skin cancer promoter but exerts this toxicity through a hitherto unknown mechanism that is different from that of phorbol esters, such as TPA (Meyer et al. 1993, 1994 Moser et al. 1992, 1993). Unlike initiation, promotion is a reversible process to a point. This implies, at least in theory, that there may be justification for setting NOAELs for promoters. [Pg.142]

The cause of AD is unknown although many hypotheses abound. The gene for one of the excessive amyloid proteins(b-type) has been associated with chromosome 21 at a point not far from a locus linked to some cases of familial Alzheimer s. Victims of Down s syndrome have an extra copy of chromosome 21 and usually fall prey to AD in their 4O s should they live to that age. However no all AD victims have a 21 mutation. Other causative theories involve accumulations of aluminum in the brain or the presence of a slow virus or an infectious protein substance called a prion. [Pg.148]

Another application of graph theory to chemistry is in chromosome analysis. Suppose a chromosome is broken into a number of pieces and each piece analyzed. If this is done a number of times, the pieces found will overlap in various ways. [Pg.24]


See other pages where Chromosome theory is mentioned: [Pg.208]    [Pg.69]    [Pg.3]    [Pg.129]    [Pg.57]    [Pg.1551]    [Pg.60]    [Pg.102]    [Pg.133]    [Pg.15]    [Pg.2]    [Pg.208]    [Pg.69]    [Pg.3]    [Pg.129]    [Pg.57]    [Pg.1551]    [Pg.60]    [Pg.102]    [Pg.133]    [Pg.15]    [Pg.2]    [Pg.504]    [Pg.242]    [Pg.583]    [Pg.176]    [Pg.19]    [Pg.14]    [Pg.282]    [Pg.88]    [Pg.132]    [Pg.308]    [Pg.46]    [Pg.489]    [Pg.490]    [Pg.122]    [Pg.400]    [Pg.210]    [Pg.408]    [Pg.698]    [Pg.492]    [Pg.80]    [Pg.1504]    [Pg.628]    [Pg.74]    [Pg.34]    [Pg.126]   
See also in sourсe #XX -- [ Pg.208 ]




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Chromosome theory of heredity

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