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Circular codes in the evolution of the genetic code

  • The composition of the structure of the genetic code is undoubtedly one of the most challenging questions open in molecular biology. A promising element in solving this question is the evolutionary development of the structure of the genetic code. Therefore, the evolution of the genetic code has increasingly become the focus of the search for medical applications to cure and prevent hereditary diseases. To further promote such research, the main motivation of this dissertation is the theoretical identification of a factor influencing the evolution of the genetic code. The first evolutionary hypothesis not disproved so far was published by Crick in 1968. His frozen accident theory states that the genetic code was generated by chance and has remained frozen ever since. However, most researchers working on the evolution of the genetic code today agree that such an efficient system cannot have appeared spontaneously. Hence, in recent years, new theories have been developed which claim to explain the origin of the genetic code. The most common ones are the stereochemical theory, the adaptive theory, and the co-evolution theory. The influence factor analyzed in this dissertation is derived from the adaptive theory. This theory postulates that evolution aimed at obtaining a code that minimizes errors resulting from mutations. However, we do not claim that other theories such as the stereochemical theory and the co-evolution theory had no influence on the evolution of the genetic code. It is rather a matter of emphasizing properties of the genetic code that can only be assigned to the adaptive theory. Summarized this work introduces properties of the genetic code which address the problems of retrieving, maintaining, and synchronizing the correct reading frame during the translation process. Translation is a subprocess of the protein synthesis. In this process the ribosome decodes the messenger RNA (sequence of nucleotides {A,C,G,T}) as codons (word of 3 nucleotides) to create a specific amino acid chain. Unfortunately, the mRNA can be decoded in three reading frames: 0, +1 and +2. Yet, only frame 0 encodes the correct information needed for the synthesis of proteins. The first practical evidence of a genetic model which can retrieve the correct reading frame is the so-called X-code. This X-code was obtained by Arqùes and Michel in a statistical evaluation of the codons in coding sequences of different species. Astonishingly, the X-code turned out to be a circular code. The advantages of circular genetic codes are incomparable. Such a circular code is a block code, i.e., a code consisting of words of a certain word length, which recognizes a reading frame error. This work introduces new properties of circular codes in general. These included the minimum sequence length to ensure the reading frame, a new classification of circular codes and new hypothetical processes inspired by the circular code theory to ensure the frameshift robustness during the translation process. With these findings, this dissertation presents a hypothetical guiding line which can be a valuable asset to the discovery of the evolution of protein synthesis.

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Verfasserangaben:Martin Starman
Gutachter*in:Christian M. MICHEL, Lutz STRÜNGMANN, Simone GIANNERINI, Alain DENISE, Elena FIMMEL, Jean-Sébastien SERENI
Betreuer*in:Christian M. MICHEL, Lutz STRÜNGMANN
Jahr der Fertigstellung:2020
Veröffentlichende Institution:Hochschule Mannheim
Titel verleihende Institution:Hochschule Mannheim
Datum der Abschlussprüfung:10.12.2020
Datum der Freischaltung:24.11.2021
Freies Schlagwort / Tag:Adaptive theory; Block-codes; Circular codes
GND-Schlagwort:Genetischer Code; Evolutionstheorie; Code Theorie
Fakultäten / Einrichtungen:Fakultät für Informatik
DDC-Sachgruppen:000 Allgemeines, Informatik, Informationswissenschaft / 000 Allgemeines, Wissenschaft / 004 Informatik
Zugriffsrecht:Frei zugänglich
Lizenz (Deutsch):License LogoCreative Commons - CC BY - Namensnennung 4.0 International