Seeing red

[The Grand Nudger]

Well, I'm playing devil's advocate here, by which I mean that I'm trying to ignore my own sense of what mind is, or ideas, and trying to see ideas purely as physical patterns which arise for certain reasons, or which are expressed in certain ways.  So right now, and only right now, I mean that an idea is a representational state, i.e. a partial mirror of an external physical reality.

Devils advocate for what or whom ?  I think that any definition of idea that does not distinguish between a rock and an idea is likely to yield poor inferences no matter what way you go with it.  

If DNA represents an idea-- which I think both you and Jorm would say it does-- then that means that mind as we experience it and ideas aren't necessarily the same thing, which would be an important philosophical conclusion we could arrive at even without appealing to qualia.

Our conceptualizations of dna are ideas.  DNA itself is an expression of organic chemistry. The concepts themselves are as much(and as little) a code for building life as bernoulli's principle is a code for building a plane.

I don't really want to define idea too narrowly, because I want to draw an analogy between an idea in the human brain, which is short-term and temporary, with other representations of state, like those implied in DNA.

A definition that's too broad runs the risk of defining nothing at all.  You probably answered your own question -in- the question above, we don;t refer to -any- representation of state as an idea. You said it yourself. Expressed in certain ways, for certain reasons. I'm sure you could draw those analogies without any fuss over whether or not dna is an idea, in any case. The things built by dna, for example, are generally temporary themselves, requiring metabolism and growth of new cells or structures to persist, as we do, as living examples of the ship of theseus.