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DNA Sculpture (Parameterised)

by cathalgarvey, published

DNA Sculpture (Parameterised) by cathalgarvey Jul 4, 2010

Featured Thing!

Description

I got featured on Thingiverse! Also, now for sale on Shapeways!

A fairly simple sculpture of DNA, built on a stand so you can use it as a nerdy desk ornament or as a teaching aid. Or as an aspirational goal, if you\'re anything like me ("I will best you yet, DNA!")

The Makerbot-printed versions are not technically correct, but all told, it's a modestly accurate representation, although the real thing is more dense and complex. And constantly under assault/revision by proteins and nosy scientists. I've included a version of the molecule which roughly corresponds to the common, active form in cells, called "B-DNA".

If you've only ever seen those pictures of DNA that look like a ladder twisted along its virtual axis, welcome to the slightly quirkier reality! If you like this kinda stuff, check out DIYbio.org. If you live on the West Coast and want a Bio-Hackerspace to play in, support "Biocurious" on Kickstarter!

I have put this model on Shapeways for those who might want a premium model in acrylic, glass, steel or plated gold! http://www.shapeways.com/model/134213/dna_sculpture.html

Recent Comments

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Cathal, what would need to be done to make this model more accurate (at least for right-handed DNA)
do you mean you changed the backbone to be thicker?
In the definition of OvoidBase I changed:

sphere(r = BaseLength/2);

to

rotate([90,0,0]) cylinder(r = BaseLength/2, h=BaseLength-2, center=true);

so it still does get flattened somewhat by the surrounding scale command. I put the -2 in the height and I also bumped BackboneRadius to 5.2 to make the seam between the base and the backbone smoother.

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Instructions

There are two makerbottable versions, the "Left-handed" and "Right-Handed" spirals. Right-handed corresponds to native B-DNA, the active form in most cells, and Left-handed corresponds to Z-DNA, the generally inactive form. Both are technically inaccurate with regard to spiral winding, but that's easy to fix in the script if you have a machine capable of supported printing. See here for information on accurate structure: http://en.wikipedia.org/wiki/Z-DNA#Comparison_Geometries_of_Some_DNA_Forms There is a third model representing "B-DNA" as accurately as I was willing to spend time on. :)

There's a fair amount of cleanup to do, thanks to the first layer or two of each base pair being dropped into thin air. Better skeinforging might lead to better models. A firmly supported build platform would help too, which I lacked in printing mine.

Note: The OpenSCAD file contains support for cuboidal bases and ovoid backbones, as well as options to vary the spacing between strands and their relative rotation from one another. And how twisty they are. And how densely to pack in the bases. Basically the works, it's OpenSCAD after all.

IMPORTANT: After you have printed, remember to post under "I made one!" on Thingiverse. If you don't, you'll develop nasty boils and members of whatever gender you are into will shun you.

Cathal, what would need to be done to make this model more accurate (at least for right-handed DNA)
For the bases of mine I altered the ovoid to be a cylinder, so that it was always an easy stretch across from one backbone to another, and it came out pretty well.
do you mean you changed the backbone to be thicker?
could you post the modification with the cylinder bases? :) thanks!
In the definition of OvoidBase I changed:

sphere(r = BaseLength/2);

to

rotate([90,0,0]) cylinder(r = BaseLength/2, h=BaseLength-2, center=true);

so it still does get flattened somewhat by the surrounding scale command. I put the -2 in the height and I also bumped BackboneRadius to 5.2 to make the seam between the base and the backbone smoother.
You see, that would have been the clever thing for me to do! :P I wanted it to be all ovoid-ish laterally but not vertically, and should have thought to truncate the underside to make it flat so the bridging didn't screw up.

The cylinders turned out really well though, I'm impressed! Thanks for sharing the picture. :)
Fine piece of art.
Did you purposely make it left handed?

Also nice work, it's amazing that the bases came out as good as they did.
There is a good reasons for that.
I am have the dumb. It is an real conditions.

So no, I didn't mean to make it left handed, although in my defense, both conformations occur in nature! :P
http://en.wikipedia.org/wiki/Z-DNA

Time to recompile a right-handed edition..
All Thingiverse STL renderings are mirrored.

I guess Zach forgot a - sign :-D
At least in this case, I actually did make the helix backward as you can see in the printout. Native "euchromatic" DNA is a right-handed spiral, whereas mine is left-handed. You also find the contorted left-handed spiral in cells in areas where the DNA is generally inactive, called "heterochromatin". It is are folded into that unusual conformation to prevent proteins from accessing it (because they are generally built to spiral right-handed to fit euchromatin).

I'm reuploading the files so users will have their choice of handedness. They aren't exactly representative; the native right-handed spiral is far tighter in nature, but the makerbot wouldn't be able to handle it without support material yet. The left handed form is roughly as it is here, but with
more base-pairs.
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