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<p>neo ancient wrote:
<blockquote TYPE=CITE>Lord Snooty <firstname.lastname@example.org> wrote in
<p>> It seems clear that a Boolean AND function occurs in nature. Also,
<br>> is clear that, since both inhibition and excitation of pathways
<br>> exists, we can have a NOT gate equivalent. But does an OR gate exist
<br>> in natural protein pathways? An XOR gate?
<p>you can make an OR gate out of AND and NOT gates.
<p>! (!A & !B) == A | B
<p>the XOR gate is also equivalent
<p>(A | B) & !(A & B) == A ^ B
<p><br>Yup, the first is called de Morgan's law. But I'm talking fundamental
OR behaviour versus fundamental AND behaviour in a single subsystem or
node (actually the transcription machinery). To be precise for a
<br>The system requires both inputs to be present to create an output =
<br>The system requires either or both inputs to be present to create an
output = fundamental OR
<p>To be more precise again: "to be present" means that the physical molecule
is actually interacting, in either an inhibitory or an excitatory manner.
Similarly, the "output" can only denote the activation of transcription,
not its inhibition, and the resultant mRNA product.