Re: Incredible evolution

On Aug 11, 12:29 pm, Glenn <GlennShel...@xxxxxxx> wrote:
On Aug 11, 4:58 am, Ron O <rokim...@xxxxxxx> wrote:



On Aug 10, 8:55 pm, Glenn <GlennShel...@xxxxxxx> wrote:

http://www.sciencedaily.com/releases/2007/08/070809130025.htm

"Modification of histones has been studied for some time, now we are
moving to understand the modification of something that modifies
histones," Shen says of INO80.

Shen's research is conducted in yeast, but the pathways involved are
conserved in all forms of life with complex cellular organization,
known as eukaryotes, right on up to humans, Shen notes."

It seems to me that repair mechanisms are essential for life. Are
there any examples of organisms that lack these complex systems?

Repair systems are found in all bacteria and eukaryotes that we have
looked for them in, but they are missing from viruses. Some viruses
do not even use host repair genomic repair systems, although they
might depend on them indirectly for up keep of host translation
systems.

If you are claiming that repair systems might be required for
lifeforms, the claim is untenable at this time. You are just looking
at the extant organisms that have been in competition for living space
and resources for billions of years. We only see the survivors.

Actually I was looking at "the pathways involved are conserved".- Hide quoted text -

- Show quoted text -

The problem is that you probably have no point that you can make
relavent to whatever you want to put forward or defend. If you have
one, make it.

They seem to be talking about conservation among eukaryotes for
histone pathways. Genomes were limited in size for a couple billion
years until one lineage figured out a means to package large amounts
of DNA in multiple packets called chromosomes. All eukaryotes share
this feature, and are descended from that ancestor. Prokaryotes
developed other systems for DNA packaging, but never made the jump
past a certain amount of DNA in their genomes.

The evidence suggests that it may have taken nearly 2 billion years to
evolve this DNA handling system. No one claims that it was easy.
There is the fact that, apparently, it hasn't happened again
independently, or the Johnny come latelies that evolved something
similar could never get a foothold in the turf plowed by the first to
do it. It is a highly conserved system. The chromosomes aren't as
tightly packed in fungi as they are in, say, mammals, but the basic
packing is pretty much the same. This chromatin has to be dealt with
in pretty specific ways. You not only have to keep track of all the
DNA, you have to condense it and open it up for gene transcription and
genome replication. By the time the lineages for plants and animals
was separating the system had evolved pretty much to its present state
and has been fairly conserved since. You can look up the Histone
genes and find that there might only be a single amino acid difference
between the same gene in a pea as in humans. It took looks like it
took hundreds of millions of years to evolve this system to that
point, and there hasn't been much improvement in it for a long time.

"Conserved" is a relative term. It isn't completely conserved, but it
is conserved enough so that we can determine that everyone of our
ancestors since the single celled eukaryotes that were the common
ancestors of both plants and animals had this basic system.

Ron Okimoto

.

Relevant Pages

  • Re: Incredible evolution
    ... known as eukaryotes, right on up to humans, Shen notes." ... do not even use host repair genomic repair systems, ... at the extant organisms that have been in competition for living space ... They seem to be talking about conservation among eukaryotes for ...
    (talk.origins)
  • Re: Incredible evolution
    ... known as eukaryotes, right on up to humans, Shen notes." ... at the extant organisms that have been in competition for living space ... They seem to be talking about conservation among eukaryotes for ... of DNA in multiple packets called chromosomes. ...
    (talk.origins)
  • Re: Incredible evolution
    ... known as eukaryotes, right on up to humans, Shen notes." ... at the extant organisms that have been in competition for living space ... of DNA in multiple packets called chromosomes. ... You can look up the Histone ...
    (talk.origins)
  • Re: Chicken Junk
    ... "Human Ultraconserved Elements are Ultraselected" ... The reason for this extreme conservation remains a mystery. ... Evolutionary non-conservation provides a complementary clue about junk DNA. ... Nevertheless, as long as versions of the virus stayed around, the same ...
    (talk.origins)
  • Re: Incredible evolution
    ... known as eukaryotes, right on up to humans, Shen notes." ... do not even use host repair genomic repair systems, ... at the extant organisms that have been in competition for living space ... of DNA in multiple packets called chromosomes. ...
    (talk.origins)