Chapter category: Evolution
Extant Variations in the Genetic Code
The Genetic Code and the Origin of Life
Edited by: Lluis Ribas de PouplanaISBN: 0-306-47843-9
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Chapter authors:
Manuel A.S. Santos and Mick F. Tuite
The discovery in the 1960s of an identical genetic code in Escherichia coli, viruses and mammalian cells suggested that all living organisms use the same genetic code. The existence of a universal genetic code prompted Crick1 to propose the “Frozen Accident Theory” which states that the genetic code does not evolve. This theory was based on the assumption that in the last common ancestor, life-forms had reached a level of complexity that would not tolerate alterations in the identity of their codons. That is, once proteins had acquired a certain level of functionality, any alteration in codon identity would introduce structural and functional disruption with a high probability that this would be lethal or highly detrimental.
Additional chapters from this book:
The Evolutionary History of the Translation Machinery
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Adaptive Evolution of the Genetic Code
R.D. Knight, S. J. Freeland and L.F. Landweber
All known genetic codes use 4 bases and 20 amino acids, but many other bases and amino acids have been synthesized and/or found in organisms. The coding relation ships between particular trinucleoti...
Ribozyme-Catalyzed Genetics
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RNA World research in recent years has sought to establish whether ribozymes have the catalytic versatility and potency to transmit genetic information and to sustain a credible metabolism. At a min...
The Nature of the Last Common Ancestor
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Until the late 1970’s cellular evolution was assumed to be a continuous, unbroken chain of progressive transformations that begun with the emergence of life itself and contin ued until the endosymbi...
Extant Variations in the Genetic Code
Manuel A.S. Santos and Mick F. Tuite
The discovery in the 1960s of an identical genetic code in Escherichia coli, viruses and mammalian cells suggested that all living organisms use the same genetic code. The existence of a universal g...
Functional Evolution of Ribosomes
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Protein synthesis is a complex process that constitutes the last step of gene expression. The first studies that correlated this cellular activity with certain “ribonucleoprotein par ticles” present...
Expanding the Genetic Code in Vitroand in Vivo
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Insight into biological function at almost every level, from catalysis to signal transductionto structure, requires a detailed understanding of proteins, biopolymers of remarkable di-versity assembled...
Origin and Evolution of DNA and DNA Replication Machineries
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The transition from the RNA to the DNA world was a major event in the history of life. The invention of DNA required the appearance of enzymatic activities for both synthe- sis of DNA precursors,...
Early Evolution of DNA Repair Mechanisms
Jocelyne DiRuggiero and Frank T. Robb
DNA repair is critical for the maintenance of genome integrity and replication fidelity in all cells, and therefore was arguably of major importance in the Last Universal Cellular Ancestor (LUCA...
The Early Earth
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The Earth is so far the only place in the Universe where life is known to exist. Is the Earth special, or are there other places both in our own solar system and beyond where life may have origi...
Reconstructing the Universal Tree of Life
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The universal tree of life depicts the evolutionary relationships of all living things by grouping them into one of three Domains of life; the Archaea (archaebacteria), Bacteria (eubacteria) and ...
The Scope of Selection
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We have estimated the maximal size for an RNA motif recoverable from selection-amplification for new RNA activities, under conditions that span those in present laboratory use. The number of s...
