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On 23/05/2020 00:56, bill w wrote:<br>
<blockquote type="cite"
cite="mid:mailman.6.1590191793.23343.extropy-chat@lists.extropy.org">Completely innocent
and ignorant question: how far are we from examining a gene and
predicting what it will do? If we could do that, we could design
genes, splice them in and do our own evolution, eh</blockquote>
<br>
Bill, I'd say we are very, very far from this, in general, when
faced with an unfamiliar gene.<br>
<br>
When faced with a familiar one, where we already know what it will
do under specific conditions, we can probably tell that changes to
it will make it dysfunctional.<br>
<br>
One of the problems is that genes are not as simple as they are
usually made out to be. A 'gene' is just a sequence of DNA that
codes for a protein, but that's just the beginning of things, and is
not even strictly true in many cases. A gene can code for a fragment
of a protein. Or a fragment of a number of different proteins. Or
the precursor to one or several proteins, or slightly different
versions of the same protein, depending on how its transcripted RNA
is cut up into smaller bits, and recombined with some of these bits,
or bits from other genes...<br>
<br>
Then, the end-product of translating this RNA into a protein often
goes on to do different jobs in different places under different
circumstances.<br>
<br>
Finally (or probably not finally, there may well be other mechanisms
at work that I'm not aware of), the gene is subject to control over
if and when it's expressed at all, by other stretches of DNA
(usually 'non-coding' DNA), and chemical groups that sit on the DNA
strand (this is what's known as epigenetics), which are themselves
gene products, which are subject to control... And so-on. There is
even evidence that the same stretch of DNA can code for more than
one thing, with what you get depending on where you start
(frame-shifting), a little bit like this string of letters
representing different sentences, depending on where you start, if
you make the sentences by selecting every third letter: <font
color="#ff0000">A</font><font color="#004080">A</font>T<font
color="#ff0000">R</font><font color="#004080">B</font>W<font
color="#ff0000">E</font><font color="#004080">I</font>O<font
color="#ff0000">D</font><font color="#004080">G</font>E<font
color="#ff0000">C</font><font color="#004080">D</font>G<font
color="#ff0000">A</font><font color="#004080">O</font>G<font
color="#ff0000">R</font><font color="#004080">G</font>S. Genetics
is full of tricks like this.<br>
<br>
It's basically a massive spaghetti program, written in a language we
only partially understand. Predicting what one gene will do is like
predicting what will happen if you change one variable in a
monolithic, multi-million-line program written in BASIC, with heavy
reliance on GoTo statements. In fact, I'd say it's worse than this.<br>
<br>
It's probably no more possible to tell what a single unknown gene
will do that it is to tell what a particular unknown pattern of
cells will do in Conway's Game of Life. The only way to find out is
to run the program and see what happens. So we'd have to have a
massive simulation of all the biochemistry of an entire organism
before we could tell what a single gene does, and we are a very long
way from that.<br>
<br>
This is why no-one has made more than trivial progress with genetic
engineering to produce novel features. People talk excitedly about
using CRISPR to give people things like an extra thumb, or extend
our vision into the ultraviolet. We have no clue how to do things
like this, and we would be fumbling in the dark in a room full of
mantraps to even try it.<br>
<br>
I very much doubt that genetic engineering is the way to enhance
ourselves in significant ways. I hope I'm wrong (because it would
mean that we are, collectively, MUCH cleverer than I suspect we
are), but I have severe doubts.<br>
<br>
<pre class="moz-signature" cols="72">--
Ben Zaiboc</pre>
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