One thing to keep in mind is thatby GreenMan (no login)
There is an important structural difference between DNA and RNA. The all-important tertiary shape of proteins Michael Calkins mentioned above is what determines how they will interact with various substances, with each other, etc. The double-helix structure of DNA limits the possible number of shapes it can assume, and therefore the number of different ways it can interact with other molecules (the double strand means that all the available places where it might connect to itself are taken up by connections with places on the complimentary strand, so while it will curl up into a knot, it won't do so in any reliable way). But RNA is single-stranded, which means that it is capable of tricks like this that wouldn't work with DNA. The "RNA world" hypothesis (not much better than conjecture at this point, really) is based on the proposition that RNA molecules (or some primitive precursor) could have stumbled upon configurations at the level of tertiary structure that would have caused them to interact with other molecules in a way roughly analogous to the way proteins do.
|Response Title||Author and Date|
|The most interesting thing about many protein molecules||on Aug 30|
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