How did the DNA evolve

[Micaiah]

I'm interested to hear discussion on how the DNA of present life forms evolved.

A common example that I've heard is duplication of a gene and then subsequent mutations to that duplicated gene.

Feel free to give actual examples of such changes.

 

[notto]

Are you familiar with polyploidy in plants?

 

[FreezBee]

I'm interested to hear discussion on how the DNA of present life forms evolved.

A common example that I've heard is duplication of a gene and then subsequent mutations to that duplicated gene.

Or incorrect duplication - rather than subsequent mutations.


cheers

- FreezBee

 

[Loudmouth]

The "Nylong Bug" is an oft referenced example of evolution in action. A species of flavobacterium evolved the ability to digest small nylon oligomers. These bacteria were found in a nylon factory in Japan. As it turns out, the ability to digest nylon oligomers was a direct result of mutations. These mutations occurred in genes that had strong similarities to other, already existant genes. You can read up on the nylon bug by going to www.pubmed.com and entering "nylon flavobacterium" as your search criteria. Here is one of the more important abstracts:

Microbiology. 1995 Oct;141 ( Pt 10):2585-90.Related Articles, Links

[size=+1]A plasmid encoding enzymes for nylon oligomer degradation: nucleotide sequence and analysis of pOAD2.[/size]

Kato K, Ohtsuki K, Koda Y, Maekawa T, Yomo T, Negoro S, Urabe I.

Department of Biotechnology, Osaka University, Japan.

The entire nucleotide sequence of nylon oligomer degradative plasmid pOAD2 from Flavobacterium sp. KI723T1 was determined. pOAD2 comprises 45519 bp, with a 66.6 mol% G+C content. The precise loci of the four nylon oligomer degradation genes, namely nylA (6-aminohexanoate-cyclic-dimer hydrolase gene), nylB (6-aminohexanoate-dimer hydrolase), nylB' (a gene having 88% homology to nylB) and nylC (endo-type 6-aminohexanoate oligomer hydrolase), and five IS6100 elements were identified on this plasmid. Comparison of the sequence of pOAD2 with those in the GenBank and EMBL databases revealed that the deduced amino acid sequences from eight regions of pOAD2 had significant similarity with the sequences of gene products such as oppA-F (oligopeptide permeases), ftsX (filamentation temperature sensitive), penDE (isopenicillin N-acyltransferase) and rep (plasmid incompatibility). A functional map of pOAD2 is presented. emphasis mine

 

[Dr.GH]

A more basic approach is the evolution of the codon triplets in the first place:
Trifonov EN. The triplet code from first principles. J Biomol Struct Dyn.
2004 Aug;22(1):1-11.

Abstract
Temporal order ("chronology") of appearance of amino acids and their
respective codons on evolutionary scene is reconstructed. A consensus
chronology of amino acids is built on the basis of 60 different criteria
each offering certain temporal order. After several steps of filtering the
chronology vectors are averaged resulting in the consensus order: G, A, D,
V, P, S, E, (L, T), R, (I, Q, N), H, K, C, F, Y, M, W. It reveals two
important features: the amino acids synthesized in imitation experiments of
S. Miller appeared first, while the amino acids associated with codon
capture events came last. The reconstruction of codon chronology is based
on the above consensus temporal order of amino acids, supplemented by the
stability and complementarity rules first suggested by M. Eigen and P.
Schuster, and on the earlier established processivity rule. At no point in
the reconstruction the consensus amino-acid chronology was in conflict with
these three rules. The derived genealogy of all 64 codons suggested several
important predictions that are confirmed. The reconstruction of the origin
and evolutionary history of the triplet code becomes, thus, a powerful
research tool for molecular evolution studies, especially in its early stages.

This extended the review by Dworkin, Lazcano, and Miller
Dworkin JP, Lazcano A, Miller SL 2003 The roads to and from the RNA world. .J Theor Biol. 2003 May 7;222(1):127-34

The historical existence of the RNA world, in which early life used RNA for both genetic information and catalytic ability, is widely accepted. However, there has been little discussion of whether protein synthesis arose before DNA or what preceded the RNA world (i.e. the pre-RNA world). We outline arguments of what route life may have taken out of the RNA world: whether DNA or protein followed. Metabolic arguments favor the possibility that RNA genomes preceded the use of DNA as the informational macromolecule. However, the opposite can also be argued based on the enhanced stability, reactivity, and solubility of 2-deoxyribose as compared to ribose. The possibility that DNA may have come before RNA is discussed, although it is a less parsimonious explanation than DNA following RNA.)

The origin and order of appearence in the genetic code was, as shown by Trifonov well described by a minimum of physical constraints:

With the derived consensus chronology of amino acids and the three very basic rules at hand (thermostability, complementarity and processivity) the reconstruction turned out to be a smooth and enjoyable journey.

(I over simplified a little bit. So sue me).

 

[TheBear]

Don't know fully. There are knowledge gaps.

 

[notto]

Don't know fully. There are knowledge gaps.

Correct. A better question would be 'How does the evidence suggest that DNA evolved'. This would avoid the creationist tactic that I'm sure will be displayed in this thread of requireing millions of years of evolution to be evidenced in a single lab experiment.

 

[Uphill Battle]

Correct. A better question would be 'How does the evidence suggest that DNA evolved'. This would avoid the creationist tactic that I'm sure will be displayed in this thread of requireing millions of years of evolution to be evidenced in a single lab experiment.

which can never happen. (which as a YEC I find even less convincing.... the fact that "millions of years" can be used as reasoning for why there is no clear cut evidence, only indicators.)

 

[notto]

which can never happen. (which as a YEC I find even less convincing.... the fact that "millions of years" can be used as reasoning for why there is no clear cut evidence, only indicators.)

There is 'clear cut evidence' from the fossil record to our DNA. The evidence points to common descent. The evidence that it has been going on for millions of years is completely independent and was determined before the theory of evolution was even proposed.

What would 'clear cut evidence' look like to you? What would you accept?

(my guess is that you are looking for the satisfaction of your own strawman or something that would actually falsify evolution if it were found, not support it).

 

[TheBear]

Correct. A better question would be 'How does the evidence suggest that DNA evolved'. This would avoid the creationist tactic that I'm sure will be displayed in this thread of requireing millions of years of evolution to be evidenced in a single lab experiment.

That plus - if we don't have full knowledge of something, then God did it.

 

[Blizzard1]

Some basic chemistry will teach you that atoms and molecules collide together and form other molecules (or ionic compounds, in some cases), often much larger than the original if carbon is involved. Why do some people have such a hard time understanding this? Resarch monomers and polymers.

 

[Uphill Battle]

There is 'clear cut evidence' from the fossil record to our DNA. The evidence points to common descent. The evidence that it has been going on for millions of years is completely independent and was determined before the theory of evolution was even proposed.

What would 'clear cut evidence' look like to you? What would you accept?

(my guess is that you are looking for the satisfaction of your own strawman or something that would actually falsify evolution if it were found, not support it).

we were talking about DNA, right? did the first cellular life have the double helix? if yes, how did it come about? if no, how did it come about? I just feel that those "knowledge gaps" are larger than you are willing to admit.

 

[one love]

which can never happen. (which as a YEC I find even less convincing.... the fact that "millions of years" can be used as reasoning for why there is no clear cut evidence, only indicators.)

Yes millions of years to research, but how long have humans been researching DNA? 50 years? People have been worshipping gods for how long? 50k years? And yet science, within a few hundred years, knows something that the religous people could not figure out over tens of thousands of years. Amazing that once the church stopped demonizing science and killing peoples how stuff happened.

 

[Uphill Battle]

Yes millions of years to research, but how long have humans been researching DNA? 50 years? People have been worshipping gods for how long? 50k years? And yet science, within a few hundred years, knows something that the religous people could not figure out over tens of thousands of years. Amazing that once the church stopped demonizing science and killing peoples how stuff happened.

I know there's a argument fallicy in there somewhere.... I just can't remember which one it is.

 

[Loudmouth]

we were talking about DNA, right? did the first cellular life have the double helix? if yes, how did it come about? if no, how did it come about? I just feel that those "knowledge gaps" are larger than you are willing to admit.

We don't know and will never know. DNA doesn't fossilize for long periods of time. However, hypotheses about how organisms can come about can be tested. This is as close as we will ever get to knowing.

 

[Uphill Battle]

We don't know and will never know. DNA doesn't fossilize for long periods of time. However, hypotheses about how organisms can come about can be tested. This is as close as we will ever get to knowing.

so I guess the OP can never really be ansered then. Doesn't matter, I wasn't planning on making any assertions about it anywho.

 

[Loudmouth]

so I guess the OP can never really be ansered then. Doesn't matter, I wasn't planning on making any assertions about it anywho.

The only question that can be answered is whether or not replicating chemical reactions can arise from non-replicating chemicals. Right now, RNA seems to be the best bet as it can make more RNA while still being a genetic molecule. However, better options may come about in the future.

 

[Illuminatus]

Next drive-by poster will be forcibly castrated with a hot spoon.

 

[Edmond]

There is 'clear cut evidence' from the fossil record to our DNA. The evidence points to common descent. The evidence that it has been going on for millions of years is completely independent and was determined before the theory of evolution was even proposed.

What would 'clear cut evidence' look like to you? What would you accept?

(my guess is that you are looking for the satisfaction of your own strawman or something that would actually falsify evolution if it were found, not support it).

You seem to misinterpreting common design as common decent. The idea of common descent is a ridiculous illusion of cleverlution.

------------------------------------

 

[Uphill Battle]

Next drive-by poster will be forcibly castrated with a hot spoon.

drive by poster? nah.... basically put, the OP can't be answered, 'cause we'll "never know."