Those of you who happen to be World War II buffs probably know a lot about the enigma machine. This machine was used before and during WWII by the Germans to encrypt and decrypt secret messages. In the 1930s, Polish cipher experts began working on breaking these codes and passed the information to the British before WWII began.
There is a neat website you can use with your students called “Enigma and the Code Breakers“. Here there are pictures of the machine, a description of how it worked, and more. REALLY interesting stuff.
There is also a site with an Enigma simulator (make sure your Java is working properly) that you can have your students go to, type in a message, and then see how it would be encoded. Neat!
So, what does this have to do with science, and more specifically, DNA?
I used these sites this year at the start of our DNA unit to demonstrate what it means for something to be encoded, what a code is, what decoding means, etc. I used it in conjunction with this BBC “Decoding Humanity” site and had the students compare how both enigma and DNA are codes.
I imagine you could probably use this type of information in conjunction with a history teacher at your school to create some sort of neat cross-curricular unit.
Here’s a quick and easy way to get your students out of their desks for just a few minutes and demonstrate DNA structure at the same time. It will also take very little preparation time on the part of the teacher, too (always a bonus). This should be done after discussing the basics about DNA:
- It’s a nucleic acid.
- It’s made of monomers called nucleotides.
- Each nucleotide in DNA has 3 parts–a 5 carbon sugar, a phosphate group, and a nitrogenous base.
Give about half of your students a nitrogenous base. You can either write the letters A, T, C, G on notecards and tell the students the base-pairing rules, or you can get more elaborate and create complementary shapes for A and T, and C and G and have them figure it out.
Line up these students with bases and tell them to place the base in their left hand and hold it out to the side. They must then put their right hand on the shoulder of the person in front of them. Their bodies represent the 5 carbon sugar (deoxyribose) and their right hand stretching out represents the bond holding the backbone of the molecule together.
Next, tell your other students to grab a base and line up next to the others to create the complementary strand. They will automatically try to put the bases in their right hand and stand facing the same direction as the original line of students. Say, “No, remember, the bases should be in your LEFT hand.” After a puzzled moment, they’ll figure out that they have to face the opposite direction to make this work, and then you can tell them that they’ve just demonstrated one of DNA’s most important properties–the strands are anti-parallel. 🙂
Most high school biology textbooks contain a brief description of the history of DNA research. Stduents read a little bit about Francis Crick, James Watson, Maurice Wilkins, and sometimes Rosalind Franklin as well. Dramatize this for your students by showing clips from the film “Life Story”, starring Jeff Goldblum: