Re: DNA varies widely between closely related organisms


<whitesickle@xxxxxxx> wrote in message
news:drlnbf$2ed0$1@xxxxxxxxxxxxxxxxxxxxxx
>
> [edit]What is Junk DNA?
> There are a number of different types of DNA classified as junk DNA.
>
> Pseudogenes
> Transposons
> Short interspersed elements (SINEs)
> Long interspersed elements (LINEs)
> Highly conserved non-coding non-essential DNA
> Repetitive DNA (other types, e.g. SINEs may be included in this
> category)
> The relative proportions of various kinds of DNA in the human genome is
> shown in this figure:

I'm not sure "junk DNA" is an apt or wise term for something we do not
understand very well.
We don't know much about it's role as a support structure for the more
active genes, or it's role as a repository of inactive genes, or as a buffer
against DNA-damaging factors. I'm sure there's a world of study in that
area for those who choose to explore it.

We forget that life is a product of natural forces, not intelligent design.
It doesn't think like a designer about "economy of code." An analogy is
Microsoft's earlier versions of Windows code. The code had been
patched-over so many times, that the size of the operating system had become
bloated to millions of lines of code. They do, however have the option of
starting over again with clean code, and introducing a new operating system.

If you think Microsoft is bad for patching, nature is much worse. It doesn't
have the option of starting over. It has to add-on or delete. It's not
usually a true deletion, but an inactivation, thereby making it "junk DNA."
When a new gene appears, it's probable that it came from a modified piece of
"junk DNA" that becomes useful again after many generations of remaining
dormant.



.

Relevant Pages

  • Re: Non-Coding DNA preserved by genetic drift?
    ... > supersede natural selection as the dominant evolutionary force, ... > Junk DNA costs energy to duplicate and to carry around as part of each ... > were plotted against the species' total genome sizes. ... > population sizes, more genes, more junk DNA and longer-lived gene ...
    (sci.bio.evolution)
  • Non-Coding DNA preserved by genetic drift?
    ... "The data suggest it is genetic drift (an evolutionary force whose main ... supersede natural selection as the dominant evolutionary force, ... Junk DNA costs energy to duplicate and to carry around as part of each ... population sizes, more genes, more junk DNA and longer-lived gene ...
    (sci.bio.evolution)
  • Re: Role of Junk DNA
    ... When researchers began mapping the genome, ... startled to find that humans have only 25,000 active genes. ... But researchers are now finding this junk DNA, ... by geneticists, may actually not be junk at all. ...
    (talk.origins)
  • Re: Role of Junk DNA
    ... When researchers began mapping the genome, ... startled to find that humans have only 25,000 active genes. ... But researchers are now finding this junk DNA, ... by geneticists, may actually not be junk at all. ...
    (talk.origins)
  • Re: Role of Junk DNA
    ... When researchers began mapping the genome, ... startled to find that humans have only 25,000 active genes. ... But researchers are now finding this junk DNA, ... by geneticists, may actually not be junk at all. ...
    (talk.origins)