Re: molecuar biology (fwd)

Dick Fischer (
Thu, 09 May 1996 23:25:58 -0500

At 05:39 PM 5/9/96, Prof. Pun wrote:

>I can summarize several issues that
>molecular biologists have to deal with when they attempt to explain the
>(1) There is a widely accepted consensus among molecular evolutionists
>that the rate of molecular evolution, i.e. the rate of change in the
>macromolecules that define life such as nucleic acid and protein, and
>the rate of macroevolution, i.e. the rate of appearance of new phyla as
>judged by their first appearance in the fossils and the advancement of
>fossil features, are independent of each other. The former proceeds at a
>relatively constant rate, according to most accounts, and the latter
>proceeds at an erratic rate, (i.e. the Cambrian explosion). This is an
>enigma for modern biology which by and large depends on the Central Dogma
>of Molecular biology, i.e. gene determines morphology or genetic changes
>reflect morphological changes.
>(2) To resort to the relatively rare genetic loci which are involved in
>regulation to account for the above discrepancy, neoDarwinists still have
>to wrestle with the following problems:
> 1. Regulatory elements well defined in bacterial system only
>control the synthesis of proteins that are involved in a single
>function, i.e. the utilization of a specific sugar when its is present.
>To account for the sudden explosion of the Cambrian fossils, regulatory
>mutations will have to account for the wholesale CREATION of not only new
>body plands but NEW LIFE (single cell to multicellular organisms).
>Moreover, regulatory system in bacteriaphage works in a self regulating
>fashion in which mutliple mechanisms use the same region of DNA, i.e. the
>same trigger can turn on two mutually exclusive genetic pathways such as
>bursting the cell or keeping the cell alive by burrowing inside the
>chromosome. The entire system will have to be changed drastically in
>order for the system to evolve to a differnent regulatory stage.
>Regulatory systems in higher form of life including the HOX system are
>tightly coordinated such that the whole system work together as a unit,
>i.e. the products of one gene or one cell turns on a serious of other
>gene or cells. Again an integration of these system cannot be changed by
>a stepwise small mutations. Drastic changes such as the loss of gain of an
>entire system is necessary. However, such changes are always lethal to
>the organisms.
> 2.There was hardly any living systems before the Cambrian explosion for
>the regulatory mutations to occur. The more enigmatic problem is to
>account for the abiogenesis of the first cell in the absence of genetic
>mechanisms that only occur in living systems. 4 unsolved problems have
>to be dealt with when neoDarwinists tackle with the molecular evolution
>of the first cell:
> i. polymerization of molecules is only an assembly but not
>the source of information.
> ii. no account for the switch from EXTERNAL control in
>the primordial condition to INTERNAL control of the first cell, which can
>adapt to the different environments.
> iii. primordial conditions of synthesis is metastable and
>does not persist to facilitate building up of complexity necessary for
>the evolution of the first cell.
> iv. thermodynamics favors the destruction rather than
>build up of order in the absence of living systems.
> 3. Comparisons of various macromolecular sequences lead to many
>erratic groupings of living systems, i.e. rRNA sequencing lead to only 3
>groups in the living world, groups as disparaging as worm, horse, pigeon,
>turtle, carp, lamprey can be all close relatives to each other. Only 1%
>genetic difference separates human from Rhesus Monkey. The majority of the
>DNA sequences in higher forms of life are repetitive and non-functional.
>What mechanisms can be postulated to include the minute genetic
>differences among these groups to account their vast morphological and
>physiological differences.
>The molecular tools only allow us to amplify and magnify our genetic
>materials. Without an ideological breakthrough such as polyphylectism
>where different blue prints are used for groups of life, they will only
>lead to more blind alleys.

Dear Professor Pun,

Have you met my good friend Glenn Morton? He just loves to field
questions like these. I am sure he is anxious at this very moment
to jump right in. Polyphylectism is one of his specialities, in fact.

So, go ahead, Glenn, I know this was addressed to me, but I don't want
all the glory.


Dick Fischer

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