[Vhin]

Okay, so first off - I apologize if this is in the wrong place. I thought about it, and this doesn't really fit too well anywhere, so I picked here, as it does relate to Organic Chemistry.

Okay, so you know the models that are sometimes used in Organic Chemistry (and inorganic, for that matter) to build molecules, with plastic spheres of different colors representing the different elements?

Well, what I want to do is use those to build a replica of DNA. Now, I know the first thing people are going to tell me - that's going to be a huge project. I also know the second thing - that it's going to be ridiculously expensive to buy enough kits to make one. My answer for both is the same - I'm not going to be doing it all at once. I'm going to buy kits and build as I have extra money and time; the best metaphor I can think of is how people make giant rubber band balls, by just adding a few at a time over a long period of time.

So, now that that's out of the way, does anyone have any suggestions for a particular model I should use? The main issue is the sheer number of different types of atoms in DNA, and I can't find very many models that have that many, much less with the correct number of, for lack of a better term, "bond holes" in them. So I need something that has Hydrogen, Oxygen, Nitrogen, Carbon, and Phosphorus. As far as I can remember, the only one that is forced to bond more times that it wants to is Phosphorus, in Phosphate, though there could be more that I'm just not thinking about.

Thanks in advance.

[Borek]

I think your best approach is not to buy ready kits, rather find a way of making your own. After all all you need is just a source of small spheres (wooden or plastic), sticks, paint and a drill.

[Dan]

I would go DIY if I was doing this project, but if you are set on buying kits, I would recommend HGS model kits:

Catalogue: http://www.hgs-model.com/model/index.html
Shop: http://www.maruzen.info/hgs/catalog/index.php

They actually sell kits to make DNA displays (as well as other macromolecules) for 500-600 USD. I think these have individual pieces for phosphates, deoxyribose etc. so you do not build them atom by atom.

I would still recommend their chemistry kits if you're going atom by atom. All the P will be tetrahedral, so you can just paint the tetrahedral atoms a different colour for P (you can buy brown P atoms from HGS). Most of the HGS kits will have 4-5 colours and each atom will have enough holes drilled to allow you to choose the hybridisation geometry of an atom.

See http://www.hgs-model.com/model/1000/10_00.html

You can also buy specific parts that you need from them, so you don't necessarily have to buy lots of kits and end up with lots of unused parts.

Here is a parts list:

http://www.hgs-model.com/model/1000/atom-p1.html

[Babcock_Hall]

There is a set of Cochranes models (GB10155?) that are specialized for biochemistry.  I have used them to make alanine tripeptides, and a colleague of mine used them to make a short stretch of DNA, IIRC.  We bought ours through Sigma Aldrich (Z184764-1KT), but I imagine that there are other suppliers.

[Arkcon]

Another very simple way to do this sort of thing is with Styrofoam craft balls, which you can find and many hobbyist or crafting stores.  You won't need to use a power drill like you would for a solid wooden ball, just a pencil.

The whole point is, just getting the bond angles correct.  The kits are pre-drilled for you, but you can do it your self with the Styrofoam balls.  Just measure and poke.

Note:  You can make your own ball and stick models, which are useful for predicting reactions, or instead, you can use Styrofoam to make a space-filling model.  http://en.wikipedia.org/wiki/Space-filling_model  Just shave the respective ball to build the model, again, at the correct bond angle.

[orgopete]

Well, what I want to do is use those to build a replica of DNA. Now, I know the first thing people are going to tell me - that's going to be a huge project. I also know the second thing - that it's going to be ridiculously expensive to buy enough kits to make one. My answer for both is the same - I'm not going to be doing it all at once. I'm going to buy kits and build as I have extra money and time; the best metaphor I can think of is how people make giant rubber band balls, by just adding a few at a time over a long period of time.

Replica of DNA? I think you should start with your calculator. DNA is a polymer. How big are you planning? The models referred to by Dan look to be about 3 ft tall for a single turn. (They have a video showing the models, including Koji Kakanishi.) Molymod has a DNA kit as well and theirs is about 3 ft tall for 17 base pairs. (I really like the Molymod models and I have acquired a number of them on eBay.) 

None the less, let's do a little calculating. There are about 10.5 base pairs per turn, a gene in bacteria contains about 1000 base pairs, if the molymod models contain 17 base pairs per 3 ft, then a bacterial gene would be 175 ft tall.

If you are thinking like the rubber band ball, I would imagine you are trying for something larger than the one sold by Staples with ~180 rubber bands for a small ball. I would suggest you either plan on laying it on its side or start by making your scaffold. (I use this just for illustration. You can use smaller models. I just think you should plan the dimensions your model can take on.)