Animal virus genetics / edited by Bernard N. Fields, Rudolf Jaenisch.

  • ICN-UCLA Symposia on Animal Virus Genetics (1980 : Keystone, Colo.)
Date:
1980
Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Animal virus genetics / edited by Bernard N. Fields, Rudolf Jaenisch. Source: Wellcome Collection.

    31/864 (page 1)
    IS-ELEMENTS AND TRANSPOSONS Peter Starlinger Institute of Genetics University of Cologne FRG A. Transposition And Evolution For a long time, mutation and recombination have been thought to be the driving^ forces of evolution. Our increased understanding of molecular genetics has let to difficulties with this concept. We have learnt that genes are DNA molecules of looo base pairs or more and that mutations consist in the substitution or addition or deletion of single base pairs. Recombination requires that homologous DNA molecules of con¬ siderable length pair. Thus, recombination does not alter the general arrangement of DNA molecules. It is only capable to exchange alleles. It is doubtful, whether these two mechanisms are capable to explain molecular evolution. How does a protein molecule with a new function evolve? If the gene for the new protein is derived from its ancestor gene by successive point muta¬ tions, these point mutations must have been accumulated either by selection or by random genetic drift. If the former is true, we must assime that the two proteins are connected by a continous series of other, functional proteins. This is un¬ likely. If, however, no such series exists, it is hard to avoid the assiomption that the first base substitutions finally leading to the new function do not have a selective value towards this goal. In this case, they must be accumu¬ lated by random drift. It is hard to imagine, how this can occur with a protein of loo amino acids or more, because the possibilities to be explored by the genetic drift in this case exceed the very large number of 2o . This problem would be relieved, when the units evolving independently ANIMAI. VTRIIS nF.NFTirS 1 Copyright © 1980 by Academic ÍYess, Inc. All rights of reproduction in any form reserved. ISBN 0-12-255850-2