Project DNA

Sarah had a project for biology class this past week to make a model of a DNA molecule.  She actually has had the assignment for a month, but waited until the last week to work on it.  In all fairness though I said I would help her with building it.  I figured it would be very easy to do, just a few styrofoam balls, some paint, and pipe cleaners.  But I was sadly mistaken.

The one requirement was that she couldn't use licorice, because apparently everyone over the last couple of years used licorice.  There are all kinds of instructions online for building a DNA molecule using food, so the teacher apparently wanted the kids to use more of their imagination, or something.  And when I was looking for things online to give Sarah some ideas, I saw several model kits for building a DNA molecule.  Some were pretty simple, and others were quite elaborate, and the cost ranged from about $25 up to over $100.  So we could have bought a model to make, but that sort of defeats the purpose.  And I wanted to keep the cost under $25 because of the supplies cost more than that, I would have been better off just buying a model.  This lead us to the craft store.

The first thought Sarah had was styrofoam balls.  But for a the two different sizes of balls we would have needed and the number of them would have been about $30.  Then we would have needed to get pipe cleaners, or dowels, and paint.  Using small wooden balls would have been even more.  So we had to go back to the drawing board.  After some thought I suggested marshmallows.  They come in different sizes and they should be easy to connect.  Sarah agreed so it was just a matter of getting supplies.  I figured we could get things for about $10.

So a week and a half before it was due we sat down to start making her model.  Our supplies were heavy gage floral wire, two bags of large marshmallows (we actually found flavored ones that were pink and blue so we didn't need to color them) a bag of small marshmallows, and a couple of packs of food coloring.  Sarah and Alison got some ziploc bags and filled them with about 25-30 little marshmallows and then put a bunch of drops of food coloring in each bag and mixed them around.  It actually colored them much better that what I thought it would.  The only problem was that like when we did the sugar cube castle a couple of years ago for Ali, the food coloring getting the marshmallows wet made them all sticky, and it was hard to get them out without them sticking together in a huge clump.  It took a little while but I helped get them all out, and then they sat overnight to dry.

The next day I helped Sarah string her large marshamllows on the floral wire and then made her "rungs"for her DNA ladder.  The assembly of the model only took about a half an hour and when it was done, I thought it looked pretty good. 

And she even finished it a few days ahead of time.

But then after going back to school the next day, Sarah found out that she made some mistakes.  And by mistakes, they were minor ones, but she wanted to make sure they got corrected before she turned it in.  She attempted to take it apart and fix it, but unfortunately, that didn't work out so well.  The model ended up falling apart, or rather not staying together too well.  So now we were in a little bit of a crisis mode.  I ended up having to run back to the store for more marshmallows, because of course, Sarah and Ali took care of our extras.  I told Sarah that I would take care of coloring her adenine, cytosine, guanine, and thymine, and then when I got home from work the next day I would help her assemble it.  This time it was a little more difficult putting it together because Sarah corrected her hydrogen bonds so we had more than one toothpick in each rung, so that when we put in the twist of the helix, they were very close to ripping loose.  I was worried that in the morning we would find that it had fallen apart. and she wouldn't have a project to turn in. 

Luckily, it stayed together, even during the drive to school.  When I dropped Sarah off, I was worried that it would come apart either walking into school or she would bump into someone in the hall in her way to the classroom.  And after seeing some of the other kids bringing their models in, I thought that Sarah's might have been a little sub-par.  But she was happy with it, and when she got home she said that it made it to class in tact and that several other kids used marshmallows, just like she did.  There were also some kids who were very extravagant with their models, and I am glad Sarah didn't go that route.  It seems like that was a little over the top for a simple high school model.  Now we just have to wait and see what kind of a grade she gets.  I think it should be pretty good.