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From: marcoj@ai.rl.af.mil (James D. Marco)
Subject: Re: recessive & dominance
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References: <3rss69$pp0@sct1.sct.fr> <marcoj-1906950935160001@fester.se.rl.af.mil> <3s7t83$h3o@PEAK.ORG>
Date: Wed, 21 Jun 1995 15:48:12 GMT
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In article <3s7t83$h3o@PEAK.ORG>, zeiglea@PEAK.ORG (Anthony Zeigler) wrote:
> In article <marcoj-1906950935160001@fester.se.rl.af.mil>,
> James D. Marco <marcoj@ai.rl.af.mil> wrote:
> >In article <3rss69$pp0@sct1.sct.fr>, sekine@world-net.sct.fr (sekine) wrote:
> >> Could anyone explain what is it?
> >**Your answer**
> >   Basically a simple thing.  Given an environment where two genes
> >-D(dominant) and R(recessive) - are capable of controlling some single
> >characteristic C, all attributes of C will be defined by D-dominant;
> >R-recessive is unused.  Hence, D is said to completely mask R. This is the
> >simplest occurrence of a genetic dominant/recessive pair.
> . . .
> >   Probably a little more than you wanted, hope it was enough.
> >                 @;-)                           marcoj@ai.rl.af.mil
> *heh* I'd like a little more...specifically, what are the forms that
> create the effect of a gene either being recessive or dominant?

You asked fer it. 

> I can think of a few ideas, perhaps someone could clarify which are possible
> and which are not? and any others...
> Gene A might code for a control protein that prevents Gene B from expressing.
> Gene A might code for a protein that binds more effectively than that of B.
          
I am not sure what you mean by "what are the forms...".  If you mean the
actual mechanism for genetic biological masking,  I dont know what it
is.  

(Im digging here since my knowledge of biology is about 20 years unused.) 

As I remember, several mechanisms effect the production of a protien from
a gene and could be used in controlling genetic masking. I should point
out that under the genetic control mechanism model I was studying, the
DNA  gene (instruction) was first used to create an RNA instruction
string, the base structure being different. The RNA moved to a production
site containing a suitable environment  - amino acids, enzymes, perhaps
subassemblies of less complex proteins, lipids, etc, in short everything
needed for the production.  A ribosome is used to hold the activator
chemicals used in the synthesis(not strictly true).  Due to a failing
memory, I will call anything needed for the production part of the
environment (Im waving my hands a lot!).  A single environmental
influence could cause a production failure or act as a trigger to start
production (perhaps the protein being produced is an inhibitor for another
process!).

Interestingly, the ribosome reads the RNA molecule much like Turings
machine reads tape, except it cannot proceed onto empty tape, the
current frame must be filled with the correct molecule, "smoothing the
road".  Hence, any missing component will halt production of a particular
protein. While not strictly sequential, there must be a 'bond' between
every molecular component to hold it together.  Note also that the
physical architecture (isomere) of a molecule is as important as the
chemical composition.
    

   1) A simple lack of supply will cause a halt to production.
   2) An inhibitor, as you speculated above, may cause a halt. Inhibiting
production of the protein directly or any item needed for production.
   3) A feedback mechanism may distort the shape of the RNA tape and
prevent production.
   4) Too much of one amino acid, needed for production, may cause the
ribosome to become inactive by blanketing.
   5) The output protein from a gene being masked may be used in the
production of the dominant protein, hence never seen except breifly during
production of the dominant protein.
   6) The dominant gene may produce a "destructor" for recessive proteins
   7)  . . .(Help me here. Any other ideas?)

I hope I answered at least part of your question. 'Chances are, there is
no one rule to fit all.  Can anyone else help me here?  
           
One thing that occured to me, but I haven't had the time to pursue, is the
multiple redundent nature of the biological instruction set.  Correct
modeling of this type of code structure may yield some interesting
benefits, especially for GA's.  Masking is an important part of this.

                     &;-)                 marcoj@ai.rl.af.mil
