BIGGEST EVER MATHS & SCIENCE LESSON GUINNESS WORLD RECORD ATTEMPT NOVEMBER 2015 Acting out the replication (copying) of DNA This ‘people maths’ activity is ideal for a large class, or whole year group, as the more participants the better. You need plenty of space, for example out of doors or a school hall. Teachers may adapt this plan and use language to suit their class. For younger learners (6 to 9 year olds) start the dance with 2 learners instead of 4. Resources: A4 paper, ideally in 4 colours, to make cuffs for each person. Method: Explain that DNA is like a very long thin ladder, twisted to make a spiral, show the class a picture and a model made earlier. Pairs of bases joined together make up the rungs of the ladder. The bases are called Adenine, Thymine, Guanine and Cytosine (referred to as A, T, G and C (pronounce Ad-­‐en-­‐ine, Thym-­‐ine, Gua-­‐
nine, Cy-­‐to-­‐sine). Your DNA code is a very long sequence of bases represented by these 4 letters, with lots of repetitions. From conception until you die your DNA code tells your body cells how to grow and develop and how to work in your body. DNA codes differ from one individual to another so that, from a little bit of us, like a hair or saliva left on a cup, scientists can tell who it came from and a lot more information about that person. We make lots of new cells every day in our bodies (for example new skin cells) and all the DNA sequences in all the cells are exactly the same. In this lesson we act out the method by which DNA reproduces itself as new cells are formed. Each person models one of the building blocks of the ladder, with head, shoulders and left arm as part of the edge of the ladder and their right arm as one of the four bases. These building blocks of DNA are called nucleotides. The class divides into 4 groups. Each learner makes a paper tube to go on their right arm, and writes the name of one base and its corresponding letter on their tube. The DNA Dance: There are strict rules: A can only pair with T, and G can only pair with C and vice versa. The dance models the way DNA replicates itself. The DNA codeword AGTC is copied in this example. You can start with any codeword. (1) The teacher chooses one person to lead the dance. In the case illustrated in the diagram, an A has been chosen as leader and 3 other people line up to start the dance. For younger learners (6 to 9 years old) start with 2 dancers rather than 4. They stand one behind the other with their left hands on the shoulders of the dancer in front to model a string of connected nucleotides. Everyone else stands around the room in their group, watching and ready to join in. To avoid confusion each group must agree on the order in which the members of their group will join the dance so that the next person is ready to join in without delay. (2) The dancers model the real DNA ladder in which the edges are directed in opposite directions. One by one 4 partners join in. They stand one behind the other facing in the opposite direction to the first line-­‐up. Their right hands hold the right hand of their partner and they put their left hands on the shoulders of the dancer in front. In this arrangement a new G joins first, then A joins in, then C, then T. The leader says ‘start’ and, with the line behind, takes four slow forward éthen four steps back ê. The other line, still holding hands, takes four steps in the same directions, but because they face the opposite direction, they first step back and then forward. (3) Then all the dancers let go of their handholds and take four steps sideways away from the other line splitting the ‘DNA ladder’ down the middle. (4) Eight new partners join them according to the pairing rule, right hands holding right hands and left hands on the shoulders of the dancer in front. Now 16 people represent two pieces o f DNA, the new one IDENTICAL to the original one. The 2 copies now move apart. Repeat this again and again until everyone in the class is taking part. (5) You can start with 2, 3 or 5 or 6 pairs rather than 4 pairs if that number suits the class better. Remind the class that any order of the base pairs (codeword) can start the dance so use different codewords. The group might work out steps to the dance and music so that it becomes pleasing for the dancers and for an audience to watch. Someone could prepare a script or commentary to explain DNA and its replication in the dance. Human DNA has 3.2 billion rungs on the ladder so the DNA strands are very long and thin and tightly packed. The population of the whole world is about 7 billion. With 3.2 billion pairs of people in the dance the process at each stage would be the same. You might like to play the DNA Song https://youtube.com/watch?v=FUA6_Ucw3i4