Sign up with GoogleA thread to discuss the evolution of life from the Last Univesral Common Ancestor (LUCA).
Current evidence suggest that the LUCA emerged about 3.5 to 3.8 billion years ago (bya) (perhaps even earlier 4 bya). The features of these organisms, as suggested by the evidence, are quite interesting.
They include:
1) A superbly optimal genetic code with the following features:
2) Biomolecular machine apparatus (some here) for the following processes (from: A minimal estimate for the gene content of the last universal common ancestor—exobiology from a terrestrial perspective):
A) Replication related machinery including;
B) Transcription/regulation
C) Translation/ribosome
D) RNA processing
E) Quality control processes (e.g. cell division control)
F) Transport/membrane
G) Electron transport
H) Metabolism
I) And several with unknown function (unknown function does not imply junk DNA though)
3) Spatial cell biology suggest that bacteria employ various "intricate and dynamic three dimensional organization that is central to their capacity to grow and divide". Bacteria are the simplest organisms that probably most resemble the state of the LUCA.
4) These organisms likely communicated like bacteria do:
'Rosetta Stone' Of Bacterial Communication Discovered
So we have abiogenesis processes that converged into a population of organisms known as the LUCA with the following properties (Figures 1 and 2):
1) Universal and very optimal genetic code
2) Quality control mechanisms and variation inducers
3) Replication machinery as well as several other molecular machine complexes crucial for survival.
4) Cell signaling mechanisms and controlled communication
Figure 1: Doolittle's tree of life and abiogenesis.
Figure 2: Convergence of abiogenesis processes into the LUCA. (bigger version)
From there onwards, the evolution of life looks something like this:
Figure 3: Tree of life (Adapted from discoverlife.org)
With repeated emergence of several interesting structures... such as the eye, echolocation, carbonic anhydrase etc.
Feel free to add more interesting information.
Current evidence suggest that the LUCA emerged about 3.5 to 3.8 billion years ago (bya) (perhaps even earlier 4 bya). The features of these organisms, as suggested by the evidence, are quite interesting.
They include:
1) A superbly optimal genetic code with the following features:
- A) No better codes out of a million biosynthetically restricted codes. (Freeland et al., 2000)
- B) The actual code is far better than other possible codes in minimizing the number of amino acids incorporated until translation is interrupted after a frameshift error occurred. (Itzkovitz and Alon, 2007)
- C) The code is highly optimal for encoding arbitrary additional information, i.e., information other than the amino acid sequence in protein-coding sequences. (Itzkovitz and Alon, 2007)
- D) The genetic code is generally regarded as the biological element least capable of evolving (Vetsigian et al.,2006)
- E) Out of all possible codes (not only biosynthetically restricted codes), the genetic code is partially optimal with regards to error minimization. The analysis only included a subset of the possible "optimality features" of the code.(Novozhilov et al., 2007)
- F) Massey (2008) found that ten thousand random codes have an average Error Minimization value of 74.5, and only 0.03% of these have equal or greater optimality than the Standard Genetic Code. He suggests that selection is at best only partly responsible for the property of error minimization.
- G) Biro (2008) have shown that the properties of the code allow it to maintain its own functional integrity.
- H) The code has the following mathematical properties (Gonzalez, 2004): Parity coding, Palindromic symmetry, Binary coding, Error-correction mechanism based on parity checking
- I) Gilis et al., (2001) have shown that with regards to minimizing the consequences of translation errors on the 3D structure and stability of proteins, only two random codes in a billion are fitter than the natural code.
2) Biomolecular machine apparatus (some here) for the following processes (from: A minimal estimate for the gene content of the last universal common ancestor—exobiology from a terrestrial perspective):
A) Replication related machinery including;
- DNA polymerase
- Excinuclease ABC
- DNA gyrase
- Topoisomerase
- NADdependent DNA ligase
- DNA helicases
- DNA mismatch repair MutS and MutT
- Endonucleases
- RecA
- Chromosome segregation SMC
- Methyltransferase (Epigenetics related enzyme)
- Methyladenine glycosylase and adenine glycosylase
- Adenine phosphoribosyltransferase
- Deoxyribodipyrimidine photolyase
- Integrase
- HAM1 Sir2 (involved invarious aspects of genomic stability and known to play a role in inducing variability)
- TatD—a recently discovered DNase
- Histone deacetylase (More epigentically related enzymes)
B) Transcription/regulation
C) Translation/ribosome
D) RNA processing
E) Quality control processes (e.g. cell division control)
F) Transport/membrane
G) Electron transport
H) Metabolism
I) And several with unknown function (unknown function does not imply junk DNA though)
3) Spatial cell biology suggest that bacteria employ various "intricate and dynamic three dimensional organization that is central to their capacity to grow and divide". Bacteria are the simplest organisms that probably most resemble the state of the LUCA.
4) These organisms likely communicated like bacteria do:
'Rosetta Stone' Of Bacterial Communication Discovered
So we have abiogenesis processes that converged into a population of organisms known as the LUCA with the following properties (Figures 1 and 2):
1) Universal and very optimal genetic code
2) Quality control mechanisms and variation inducers
3) Replication machinery as well as several other molecular machine complexes crucial for survival.
4) Cell signaling mechanisms and controlled communication
Figure 1: Doolittle's tree of life and abiogenesis.
Figure 2: Convergence of abiogenesis processes into the LUCA. (bigger version)
From there onwards, the evolution of life looks something like this:
Figure 3: Tree of life (Adapted from discoverlife.org)
With repeated emergence of several interesting structures... such as the eye, echolocation, carbonic anhydrase etc.
Feel free to add more interesting information.
Last edited:
.