Digital Biology Friday: the answer to last week's puzzle

Last Friday, we had another in the series of weird DNA structures. (You can see the first here).

I asked the audience to identify the unusual feature in this molecule. Here's the first picture:

i-2486f0aa88079d16feec632052bffaee-dna_odd.gif

tags: , , ,

Here's the answer:

Steve L. guessed it correctly. This is not just DNA, it's a DNA:RNA hybrid. I circled a 2' hydroxyl group here to make it easier to see the difference. (Remember - the "D" in DNA stands for "deoxy.") The oxygens are red and it's easiest to tell the difference between the strands if you count them.

i-3f57882538a30e79ca7d6d89c20958e0-dna_odd2.gif

For extra credit - where might you find this kind of thing in nature?

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Where in nature? During DNA transcription for protein production, I'd think. DNA strand splits apart, RNA forms up until the code for a protein has been copied over, then it heads off to manufacturing.

By G Barnett (not verified) on 03 Aug 2007 #permalink

Also during DNA replication. DNA polymerases generally can't start new strands. They can only extend from the 3' end of an existing strand, called a primer. Primers are generally made of RNA (because RNA polymerases can start new strands).

Also also, during reverse transcription to convert an RNA virus into a DNA provirus.

And in retrovirues etc ...