When Watson and Crick met Haribo

Every March, Cambridge hosts a Science Festival - two weeks of events, all free, covering everything from maths to astronomy, physics to veterinary science. Departments open their doors and invite the public in, and if you miss it, you really do miss out.

Most of the events happen on the first Saturday, and that happened to be yesterday. There's far more on offer than we can possibly manage, so we are selective about the events we attend. This year - oh joy! - we managed to fit in a lot of cell biology, my very favourite subject. So, this week, in honour of the festival, I'm going to attempt to bring back Kiddie Science. Hurrah! For background on DNA structure, in case this makes no sense at all, this is a very good place to start.

One of the groups we visited came from the institute where I used to work, and they had a fun and simple table introducing the idea of DNA structure using gummy bears. We decided to take it one stage further. If you want to have a go too, you will need a packet of cocktail sticks and a LOT of jelly sweeties.

Simply put, the most common form of DNA is a bit like a ladder that is twisted around to form a double helix. In order to model a small part of it, first we built a pair of phosphate backbones - like the outside edges of the ladder - using two colours of jelly babies and some cocktail sticks. Observant biologists will notice that the two strands are running in opposite directions with the heads of the red men pointing away from the heads of the yellow men.

The part of DNA that does the clever genetic coding are the 4 nucleotides, or bases, that fit between the long backbones like the rungs of the ladder.

These bases are of two types - the larger purines adenine and guanine (A and G), and the smaller pyrimidines thymine and cytosine (T and C). One of the crucial things to realise is that there is only a limited amount of space in between the backbones, so in order to keep your ladder legs parallel, you need to pair a large (purine) base with a small (pyrimidine) one - in this case our two choices for the large bases were red and yellow fruity bobbles, while the small bases were purple and orange gummy bears. The girls soon decided which sweets to pair together and our first molecule was made.

Now, as Watson and Crick very soon realised, this complementary base pairing gives a huge clue as to how DNA can be accurately replicated - essential if you're a cell that wants to divide properly! So, we split the two halves of the molecule apart:

and used each half as a template to build a second strand.

Now all we had to do was skewer our rungs with cocktail sticks,

Pick up the ladders and give them a twist:

to form a giant edible DNA double helix!

Apologies to 1. cell biologists; and 2. vegetarians. My DPhil supervisor would be so proud!

For Japan with Love - Bloggers Day of Silence

I cannot find words adequate to express the sorrow we're all feeling this week. The news is almost too painful to listen to, and explaining the situation to my children has been close to unbearable.

So, I'm going to join many other bloggers - many of you - in observing a day of silence tomorrow, Friday.

It's a tiny gesture, but it's something. You can find more information here, and donate here, if you can.

Keeping busy

It's been quite a week here. This is a glimpse at my worktable - a very old trolley on casters in our spare room which has a beautiful view of the village church. In the evenings the stained glass is lit up - and it's just as well I like the view as I've been spending a lot of hours here.

It started last week with a trip to the bead shop and gallery in a village north of Cambridge. I got into conversation with the manageress, and the upshot was she asked me to take in some samples of my jewellery to show her. So I have been beavering away to make a representative selection, working into the night and relying heavily on my beloved daylight lamp and trying not to go blind.

1. Rhodolite earrings, 2. rhodolite cluster necklace, 3. crochet glass pendant, 4. Banded agate and onyx pendant, 5. Banded agate and silver bangle, 6. Lagoon delica earrings, 7. Vineyard delica bracelet, 8. Vineyard delica earrings, 9. Garnet cluster necklace, 10. Green crystal pin, 11. Amethyst crystal pendant, 12. Amethyst crystal brooch, 13. Herringbone brooch prototype, 14. Brooch prototype, 15. Heavy metal delica necklace, 16. Heavy metal delica earrings

I visited today, clutching my little box of samples and trying not to feel too nervous. And guess what - THEY LIKED IT! And THEY'RE GOING TO STOCK IT!

I have to make quite a few necklaces, bracelets and earrings, and we've discussed their requirements but they're leaving the final colour and design decisions to me, because, apparently, I'm an "artist". That gave me a huge buzz, I can tell you.

So, from the start of next month, should you find yourself in Haddenham, you can pop into the Haddenham Gallery and see my stuff in the Spring Fling exhibition. Who knows, it might even give me the kick I need to put some stuff on Etsy ...