Originally posted by iamaperson
Oh, sorry, I thought Prokaryotes were unicellular organisms, and Eukaryotes multicellular ones. So whats the LUCA then, if not Procatyotic or Eukaryotic?

edit on 10.3.11 by iamaperson because: Spelling

Uni/multicellular divide does not follow the prokaryote/eukaryote divide. The vast majority of eukaryotes (both number of species and number of organisms) are unicellular. Likewise the vast majority of prokaryotes are unicellular, however there are exceptions. As to what LUCA was, nobody knows. If you ask Cavalier-Smith, he'll tell you that it was indeed a bacteria. In more mainstream view such certainty is not shown. We don't even know if LUCA had a DNA or RNA genome. Some things point to the RNA one, but likewise many things (like almost universal code) point to DNA one (thou horizontal gene transfer could explain it too).

@OP: Darwin an idiot? Right (ahem) and who are you, as in what sciene are you a doctor or professor in?

Darwin made an effort to timeline some of the biological evolution.

Think you believe someone had a magic wand, waved with it and whoohaaaa there was man!?

Sry, being a sarcastic here. But calling someone an idiot that has been studing on evolution all his life, is quite foolish, isn't it?

Namsté.

Originally posted by rhinoceros

Originally posted by iamaperson
Oh, sorry, I thought Prokaryotes were unicellular organisms, and Eukaryotes multicellular ones. So whats the LUCA then, if not Procatyotic or Eukaryotic?

edit on 10.3.11 by iamaperson because: Spelling

Uni/multicellular divide does not follow the prokaryote/eukaryote divide. The vast majority of eukaryotes (both number of species and number of organisms) are unicellular. Likewise the vast majority of prokaryotes are unicellular, however there are exceptions. As to what LUCA was, nobody knows. If you ask Cavalier-Smith, he'll tell you that it was indeed a bacteria. In more mainstream view such certainty is not shown. We don't even know if LUCA had a DNA or RNA genome. Some things point to the RNA one, but likewise many things (like almost universal code) point to DNA one (thou horizontal gene transfer could explain it too).

edit on 10-3-2011 by rhinoceros because: (no reason given)

Indeed, but as I said I did think what I thought. Now after some thinking I am thinking maybe it was whether or not they had organelles, regardless, its off topic. So we don't yet know what the LUCA was, I hope we find out soon, it would be interesting to know! Anyways, thankyou (and madnessinmysoul) for correcting me.

HA HA HA !!!! Thanks to DARWIN for one more thing!!!!!........thanks to him and his postulates.contribution to science,hints to future scientists,WE have this discussion,dont be an idiot.the man is in his grave and still winning,without white horses in 'HEAVEN'.

Originally posted by iamaperson

Originally posted by rhinoceros
Also according to current understanding prokaryotes certainly didn't evolve from eukaryotes (prokaryotes are bacteria and archaea, eukaryotes are everything else). Also eukaryotes didn't (again according to current understanding) evolve from prokaryotes, instead prokaryotes and eukaryotes share a common ancestor from which both lineages came to be. Bacteriae is the deepest rooting domain, eukarya the 2nd and archaea are the last comer. However, there was a lot of horizontal gene transfer at the time between the domains. Also some bacteria like e.g. species of planctomycetes phylum (maybe deepest branching bacterial phyla) actually have structures (various types in different species) that much resemble the eukaryote nucleus.

Oh, sorry, I thought Prokaryotes were unicellular organisms, and Eukaryotes multicellular ones. So whats the LUCA then, if not Procatyotic or Eukaryotic?

edit on 10.3.11 by iamaperson because: Spelling

LUCA, the Last Universal Common Ancestor, was probably a procaryotic (had no nucleus) single cell organism. LUCA is presumed to have exsisted because the DNA-Amino Acid transcription and transfer proccess is identical in all living organisms.

Evolution may be proven incomplete in the future. Before Einstien's Relativity, Newton's Physics was thought to be the ultimate description of reality.

Originally posted by Semicollegiate
LUCA is presumed to have exsisted because the DNA-Amino Acid transcription and transfer proccess is identical in all living organisms.

DNA-protein process is far from identical between the 3 different domains of life. For example in archaea and bacteria you've got coupled transcription and translation. In eukarya you don't. In eukarya and archae you've got introns. In bacteria you don't (apart from this special self-splicing type that is also present in eukarya). In bacteria and archaea you've got polycistronic mRNA. In eukarya you don't. In bacteria you've got sigma factors. In eukarya you don't. I can't remember how it's for archaea. Ribosomes are far from identical between archaea, bacteria and eukarya. For example in bacteria and archaea you've got the 16S subunit. In eukarya you have the 18S. Even the genetic code (of codons) isn't universal. These are just some examples that come to my mind. AFAIK currently it's assumed that LUCA's genome was probably an RNA one. Also during early days viruses transferred a lot of stuff horizontally between the 3 lineages.

Originally posted by rhinoceros

Originally posted by Semicollegiate
LUCA is presumed to have exsisted because the DNA-Amino Acid transcription and transfer proccess is identical in all living organisms.

DNA-protein process is far from identical between the 3 different domains of life. For example in archaea and bacteria you've got coupled transcription and translation. In eukarya you don't. In eukarya and archae you've got introns. In bacteria you don't (apart from this special self-splicing type that is also present in eukarya). In bacteria and archaea you've got polycistronic mRNA. In eukarya you don't. In bacteria you've got sigma factors. In eukarya you don't. I can't remember how it's for archaea. Ribosomes are far from identical between archaea, bacteria and eukarya. For example in bacteria and archaea you've got the 16S subunit. In eukarya you have the 18S. Even the genetic code (of codons) isn't universal. These are just some examples that come to my mind. AFAIK currently it's assumed that LUCA's genome was probably an RNA one. Also during early days viruses transferred a lot of stuff horizontally between the 3 lineages.

Good call, I was sloppy again.

I meant, specifically, the universality of the genetic code. Tranfer RNA uses the same codons for the various (commonly 22) amino acids in 99.9... % of living organisms.

The transcription process copies the whole gene like video or audio tape and isn't affected by the codon size, although I suspect there are more similarities than differences in the DNA ( or RNA) replication, translation and transfer processes as a whole.

Using evolution as a guide, the oldest genes are in energy production, protien synthesis, and nucleic acid maintenance. Viruses know our nuclei pretty well and could be the basic cause of our nuclei. Mitochondria produce most of our energy and appearently have some differences in their codon spelling, as compared to most organisms. So I would guess that the genes we have in common with LUCA would be protien synthesis genes or cytoplasmic glycolysis genes.

If LUCA was pre Oxygen Extinction Event then maybe we have no genes in common with it at all.

Did the Oxygen Extinction Event cause the change to DNA from RNA?

Interesting difference you site about bacteria. Could you "download" cellulosic enzyme genes into a bacteria? Maybe half of a cellulosic emzyme into each of two different cultures so the bacteria won't digest themselves. Do bacteria have no inert DNA at all, or no inert DNA within each gene?