Author: mkuiper, published on 2015-03-30
DNA model kit
DNA (Deoxyribonucleic acid) is the remarkable molecule at the core of all living things on Earth. And yet, despite its universal role in every second of our lives, few of us really appreciate its elegance and function.
This DNA scale model is intended for educational use to show its key structural features including base pairing, the classic double helix, along with the major and minor grooves. Since the model is modular, the more pieces you print, the longer you can make the model! This flexible model can also be separated into single DNA strands to help illustrate such things as base pairing, codons or even DNA replication and mutations. Use different colours for different bases and backbone to highlight the base pairing. An affordable model perfect for the classroom.
Fun fact: Each cell in our body contains a copy of our genome which is approximately 3 billion base pairs long. That means if you want to make a scale model of the DNA in just one of your cells you will need to print enough DNA to go around the Earth’s equator about one and a quarter times. And you thought Kansas was a long way to walk. (dna model scale approximately 1:50,000,000)
Edit- 5/01/2016: Re-made the design from scratch to be more robust and easier to print. Also included the openSCAD file to make your own modifications. The original version is saved as “Old_DNAmodel_Set.zip” (I don’t recommended to print these, they are just for archive purposes.)
Edit- 18/02/2016: Included a methylated cytosine to the set and updated the openSCAD file.
Edit- 4/03/2016: Included a zip file containing a stand for the DNA model. Still a work in progress! The ‘DNA grip’ part of the stand is designed to slot into the minor groove of the DNA helix.
Edit- 5/03/2016: Included a Uracil basepair for RNA modelling, and updated openSCAD file. Minor fix to Thymine base. Still working on RNA backbone piece, the additional hydroxyl to the ribose causes steric clashes in the model.
- Make sure to print out one backbone piece for each base!
A good place to start is one each of Adenine(A), Thymine(T), Guanine(G) and Cytosine(C), plus four DNA_backbone pieces. You can add more pieces to the model later.
You may also print 2 PO3 and 2 O phosphate groups to cap the ends of the double helix.
- Before assembly make sure to clear all holes of support material otherwise the pieces may not fit together or even cause splitting.
Each base should snap into its backbone by gently pushing the split pin of the base into the hole of the ribose on the backbone. (not the hole on the phosphate part, that is for later).
With the base-backbone pieces assembled, you can now try make base pairs. Gently push the thin pins into the holes of a base pair. ie) Adenine-Thymine and Guanine-Cytosine.
Next spin around the backbone parts of the base pair until they are relatively flat to the plane of the base pair and lay it on a table. One side should have a hole pointing up, the other side should have a pin pointing up. Do the same for a second base pair and lay them below the first.
You should now be able to line up the respective pins and holes of the backbones. Gently insert one backbone pin into the second backbone hole. Give a gentle twist and the hole and pin of the other side of the base pairs should line up. Print more base pairs to extend the helix.
Cap the backbone ends with the Phosphate_O and Phosphate_PO3 models.
Some notes about the build:
I find if you use an extrusion printers, you want to print the bases relatively flat to make the hydrogen-bond pins stronger. Printing narrow pins orientated vertically can be quite weak and are likely to break. I tend to find slightly larger scaled models assemble better.
Also, take care with the alignment of the backbone pieces when extrusion printing. If you find splitting occurs when you try inserting the bases printing them in a different orientation.
There is now also an included zip folder called DNA_stand.zip containing the parts to a basic stand shown in the first picture. Assembly instructions are in the zip folder. This is a work in progress and likely to change.
Tags: #MakerEdChallenge, #BiologyProject, #ChemistryProject, Art, DNA, Double_helix, Educational, molecular