Re: O.K. Heres one.

In message <d38ebb09-df91-40e9-8274-3c3b18808bdf@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>, Prof Weird <poland@xxxxxxxxxxxxxxxxxxxxx> writes
On Aug 27, 6:26 am, spintronic <spintro...@xxxxxxxxxxx> wrote:
In the so called R.N.A-world hypothesis.

RNA ribozymes, are touted as the enzymatical saviours of abiogenesis &
evolution.

But you have 2 problems.

1) For this to occur. You need *REALLY-REALLY-SHORT* ribozymes.

Certainly less than 100 bases long.

Most of ones DEMONSTRATED to have function are about that size.

You then tout, about how such a ribozyme is possible.

SINCE THEY EXIST, they are indeed possible (researchers have developed
ribozymes, and isolated them from RANDOM SEQUENCE LIBRARIES), and
there are a few naturally occurring ones (IIRC, splicing in
Tetrahymena, and viroids. Viroids are RNA-based parasites of plants
with RNA based genomes 200-400+ base pairs long, and form hammerhead
ribozymes to cleave their own genomic RNA to become infective).

Aren't (some) ribosomal RNAs also ribozymes? And at least the U6 RNA in the spliceosome?

But you then ignore 2.

2) mRNA is sometimes *thousands* of bp's long, and exhibits *NO*
enzymatical activity at all.

So ? You seem to be under the delusions that 1) your ignorant
opinions are somehow worth listening to,
and 2) that ALL RNA strings should have enzymatic activity. Both
delusions are wrong.

Why would you expect mRNA to have enzymatic activity ?

Oh, right - you're a simpleton that noticed that since ribozymes and
mRNA are both made of RNA, then mRNA MUST
have enzymatic activity too. In much the same way that since all
apples are fruits, all fruits MUST be apples.

According to R.N.A-World Hypothesis, every time DNA is transcribed,
that mR.N.A should in effect perform some enzymatical activity enroute
to being translated.

So I have a question.

Why doesn't it?

Because there is no reason to EXPECT a non-ribozymal RNA to have
activity.

Because the RNA world hypothesis DOES NOT SAY ANYTHING ABOUT mRNA; it
only states that RNA did the work of enzymes until proteins could take
over the job, relegating most RNA to a messenger role.

Wikipedia confirms what was at the back of my head - that some (Group I and Group II) introns are ribozymes (self-splicing). This would mean that, contrary to the OP's claim, some mRNAs have catalytic activity.

The first genome was probably RNA; DNA is more stable, and makes a
better 'information' storage medium.

Amino acids have a bit more versatility than nucleotides, so proteins
could take over the role of enzymes.


--
alias Ernest Major

.

Relevant Pages

  • Re: O.K. Heres one.
    ... RNA, and you have a pathological need to bellow about things you don't ... Since the RNA genome encodes functional RIBOZYMES, then any mRNA ... when transcribing this *ORIGINAL* DNA. ...
    (talk.origins)
  • Re: O.K. Heres one.
    ... that ribozymes about 100 bases long DO exist castrates his festering ... ribozymes to cleave their own genomic RNA to become infective). ... It does fold - BUT NOT ALL FOLDS GENERATE RIBOZYME ACTIVITIES. ... mRNA that doesn't fold ...
    (talk.origins)
  • Re: O.K. Heres one.
    ... ribozymes to cleave their own genomic RNA to become infective). ... Why would you expect mRNA to have enzymatic activity? ...
    (talk.origins)
  • Re: O.K. Heres one.
    ... RNA, and you have a pathological need to bellow about things you don't ... Since the RNA genome encodes functional RIBOZYMES, then any mRNA ... BECAUSE IT ISN'T BEING TRANSLATED INTO PROTEIN. ...
    (talk.origins)
  • Re: O.K. Heres one.
    ... all RNA over a certain length be a ribozyme, ... That RNA genome is then converted yo DNA. ... That DNA encodes the *ORIGINAL* Ribozymes. ... Now when you transcribe the DNA into mRNA. ...
    (talk.origins)