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	THE CHALLENGE

	For the last fifty years science educators world-wide have tried to build models of DNA. I suppose all of their efforts could be seen as attempts to 'clone' the original Waston and Crick construction of the early 1950s. The challenge over the years has been twofold: firstly, to produce a model that is an accurate representation of DNA; and secondly, to simplify the structure without sacrificing its value as a teaching aid. Today, there are many kits available for the DIY molecular biologist from the too simple to the too complex. Although a lot of personal pleasure can be gained from making these models it is often a single person's task. Constructing a single model is not normally a suitable activity for the whole class. The idea of DNA models, Lego and the celebration of 50 years of the structure of DNA resulted from a meeting with Charlotte Taylor, the 'DNA 50' Events Manager for the Medical Research Council and The Royal Society. That meeting started me thinking. Could I build a Lego DNA model that students of all ages could make? Could students working in pairs build a pair of complementary nucleotides and add their structure to their friends' structures to make a whole-class model of DNA? Why use Lego? I suppose it was because it is a famous family construction toy that can be found in nearly every home in the country and has given people of all ages hours of family fun! It is so familiar to most of us that we do not see Lego as threatening... it is a toy. Furthermore, involvement in Lego construction is nearly always a learning experience for everyone... young and old. It has been around for generations - although I do not believe that it helped Watson and Crick when they were working on their structure of DNA.

					This article appeared in the March 2003 issue of the *School Science Review*.


	THE CHALLENGE ANSWERED

I hunted out my childrens' old Lego box, sat down on the floor and tried to build a DNA model from all the different-coloured bricks that were spread out in front of me. It soon became apparent that I did not have enough of the bricks I wanted for the model and I definately needed some expert help to sort out a few technical problems. I resorted to the computer and started to surf the internet and to interrogate several web sites for information about DNA models and Lego construction. The problem was that most models made of Lego were either very small and simple or, if larger, just a double helix - a poor representation of a DNA molecule. If I was going to build a half-decent Lego model I needed some help from the experts at Legoland Windsor. I would have to go and visit them in their 'laboratories'.

One bright sunny morning I visited Guy Bagley,the Chief Modelmaker at Windsor and his team of constructors who were all very accommodating and helpful. Guy spent a considerable time talking to me and trying to convert an amateur modelmaker into a professional in just a few hours. I must admit that some of my time was also spent looking at the magnificent models his team were making. I hope my constant interruptions did not hinder their efforts too much that morning but the desire to discuss their work was irresistible. Guy was obviously a man with a natural teaching ability for some weeks later and after many hours of hard work on the carpet at work plus the assistance of a colleague, Andy Harrison, I had a model that bore some resemblance to a double helix. Another visit to Guy, and more questions to his colleagues left me happy with the construction that was evolving.

During the construction of the model there were many challenges to overcome. I wanted to make the model from the standard bricks that are available to anyone - the same philosophy behind all Lego models that are built by the Legoland constructors. The model had to be as accurate as I could make it yet still be simple in its design so that it could be constructed in the classroom. The base diameter of the model had to be proportional to the pitch of the model and obviously have ten base pairs per rotation. The structure had to be stable, so that it would not fall over half-way through its construction and strong enough to stand up to use in the classroom but still look like DNA. The version which I produced had to be a little bit of a compromise - some artistic licence had to be used but, I hope that in future versions I will be able to make improvements which will make my model even more accurate.


	INFORMATION FOR DIY MOLECULAR BIOLOGISTS

	The model is built on a standard 32 x 32 lug base plate (255 x 255 mm).
	The base of the helix fits across 28 lugs with a diameter of 225 mm.
	Green bricks 8 x 2 represent pyrimidines, and are paired with two red purine bricks 2 (6 x 2).
	Yellow bricks 8 x 2 represent pyrimidines and are paired with two blue purine bricks 2 (6 x 2).
	Clear bricks 2 x 2 and 2 x 3 are used to represent hydrogen bonding between the purines and pyrimidines and space between successive base pairs.
	A central tower made of two 2 x 2 clear bricks is needed to stabilise the model.
	Each base pair is offset by about 37° (it should be 36°) so a flat 4 x 4 rotation plate is needed between each successive base pair to provide the desired angle.
	Grey bricks at the ends of the coloured base bricks represent the deoxyribose molecules.
	Black bricks link the grey bricks together and represent the phosphate units in the 'backbone' of the structure.
	To hold the coloured purine and pyrimide bricks next to the clear bricks two white base plates are used - one a 14 x 2 the other a 10 x 2.
	The central column requires a single white 2 x 2 flat just above the rotation flat and beneath the long white flats to provide height.
	A small 1 x 2 grey flat which holds part of the end sugar onto the base is used to add stability to the model and stop the sugar breaking away from the base.

Click on each of the images below for diagrams showing how to make the model.



	With care and a little patience it is possible to build a classroom model with 12 base pairs. This is a fairly stable structure although the connoisseur may try for 15; this is not so stable and their are risks associated with its construction.


	THE FUTURE


	Happy with my success in the construction of a classroom model I have embarked on a larger, taller more accurate model - three times the size... a display model. I am fairly happy with the base pair structures and the hydrogen bond linkages but the sugar phosphate backbone is providing me with a challenge and is driving me back to the drawing board - the carpet floor... maybe I need another visit to Legoland!


	END NOTE


	In 1934 the company adopted the name Lego for itself and its products and the name comes from the Danish leg godt which meant 'play well'. The story is that sometime later it was realised that in Latin the word means 'I study' or 'I put together'.


	LIST OF COMPONENTS

Blue = purine; Yellow = pyrimidine

1 x yellow block (2 x 8)
2 x blue blocks (2 x 6)
3 x clear blocks (2 x 2)
1 x clear block (2 x 4)
1 x white flat (2 x 10)
1 x whit flat (2 x 14)
1 x red rotation flat (2 x 2)
1 x white flat (2 x 2)
2 x grey blocks (2 x 3)
4 x grey hinges (1 x 2 x 2)
2 x black blocks (1 x 6)
1 x grey plate (1 x 2)

Red = purine; Green = pyrimidine

1 x yellow block (2 x 8)
2 x blue blocks (2 x 6)
3 x clear blocks (2 x 2)
1 x clear block (2 x 4)
1 x white flat (2 x 10)
1 x whit flat (2 x 14)
1 x red rotation flat (2 x 2)
1 x white flat (2 x 2)
2 x grey blocks (2 x 3)
4 x grey hinges (1 x 2 x 2)
2 x black blocks (1 x 6)
1 x grey plate (1 x 2)


	WEB SITES

Eric Harshbarger's Lego website
http://www.ericharshbarger.org/lego

An exhibition model of DNA:
The Mysteries of the Lego genome
http://www.ericharshbarger.org/lego/dna.html

Children build DNA from Lego at the evolution Museum, Uppsala, Sweden.
Dinosaurs from DNA. Ingrid Kockum and Penilla Holm
http://members.aol.com/adlskelton/DNA2.html

A miniature model of DNA:
(Part of The Official Lego website)
http://www.lego.com/build/features/careers/careers01.asp


	STOP PRESS


	A giant version of John's DNA model was built at the Experimentarium in Copenhagen in late November 2003, to coincide with the visit of the British Council's 'DNA50' exhibition.


	Copyright © National Centre for Biotechnology Education, 2006 \| www.ncbe.reading.ac.uk