Ä Area: 190 ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
  Msg#: 4                                            Date: 10 Nov 97  06:33:06
  From: Surgical Steel                               
    To: All                                          
  Subj: And still more...
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
        Same disclaimer, etc.

-> E1> How would this happen, then? Mutations do more bad than good, and breedi
-> E1> by cloning isn't really going to expand your gene pool. And how long did
-> E1> the Earth Exist again, if this took billions of years?
->      It depends entirely where the mutation occurs in the DNA sequence as to
-> the result;  due to the unpredictable nature of mutations, especially in mor
-> complex and interdependent organisms such as vertebrates, any significant
-> mutation stands a greater chance of messing up an already existant trait.
-> However, considering that you (yes, YOU) are undoubtedly a mutation yourself
-> I'm not so sure that you have a good idea of what exactly a mutation *is*.
->      To sum up, just remember your words the next time you get hit by a
-> penicillin-resistant bacterium, and tell them that they aren't able to do th
->
->      Oh - and I said "millions (if not billions) of years".  It would really
-> depend on what he was talking about as a start and end point, and to be hone
-> I don't have a timeline in front of me at present.
>Ah, let's put it this way. Most mutations are bad. If a carpenter
>cemented ONE good brick for every 1000 bad ones, the house would
>surely collapse.

        Given your analogy, yes.  However, you are not accurately
        describing what happens when there is a mutation - perhaps the
        RESULT of a mutation, but not the mutation itself.

        As I said before, YOU ARE A MUTANT.  There are mutated cells in
        your body *right now*.

        We'll address this more after this next bit...

>Also, in fruit fly experiments, the second generation 'mutants'
>reverted back into normal fruit flies.

        Of course - this is in keeping with basic Mendelian genetics.
        Let me demonstrate with some basic Mendelian squares.

        (yes, this is long, but this is EXACTLY what you said you wanted
        - a basic explanation, even if it *is* more than 80 lines.  But
        I'm sure you want to understand, so I'm not worrying about it.)

        Although for this first example, I'm presuming that the mutation
        was a recessive, that bears out with the experimental results
        above.  Results when the mutation is a dominant follow as well.

M = non-mutated, dominant genet             m = mutated recessive gene

        |   M   |  M   |
    ----|-------|------|     Here we have a mutant (double recessive)
     m  |   Mm  | Mm   |     fruit fly mating with a (double dominant)
    ----|-------|------|     "normal" fruit fly.  As you can see, all of
     m  |   Mm  | Mm   |     the offspring would *appear* normal, but
    ----|-------|------|     they are carriers of the mutated gene.


        |   M   |  M   |    Here, our second-generation fruit fly mates
     ---|-------|------|    with a "normal" fruit fly - yet all the
     m  |  Mm   |  Mm  |    offspring still appear normal - and 50% of
     ---|-------|------|    them ARE double dominant "normal" flies!
     M  |  MM   |  MM  |
    ----|-------|------|


        |  M    |  m   |   It is only here, where we crossbreed two
    ----|-------|------|   of the "carriers" together that we have
     M  |  MM   | Mm   |   any chance at all (approx. 25% here) of
    ----|-------|------|   the mutation being expressed - and we ALSO
     m  | Mm    |  mm  |   have a 25% chance of a fully "normal" fly
    ----|-------|------|   being the result!


        Things change somewhat when the mutation is a dominant gene:

        M = dominant MUTANT gene        m = recessive "normal" gene

        |   m   |   m  |  Looks familiar, right?  Thing is that all of
    ----|-------|------|  these offspring are phenotypically MUTANTS.
     M  |  Mm   |  Mm  |  However, they all also carry the "normal"
    ----|-------|------|  gene... (I'm only going to do the cross
     M  |  Mm   |  Mm  |  breeding square below, I'm sure you've got
    ----|-------|------|  the hang of how to do this by now...)


        |  M    |  m   |  We're back to the 1:2:1 split - one "full"
    ----|-------|------|  mutant, two "carriers" (though in this example
     M  |  MM   | Mm   |  they "look" mutant), and one NORMAL fruit
    ----|-------|------|  fly - in the second generation!
     m  |  Mm   |  mm  |
    ----|-------|------|

        This sort of thing is why some traits "skip generations" in
        humans - pattern baldness, cancer, and the like.