DNA or deoxyribonucleic acid is the foundation of all life. The double helix structure allows for an infinite combination of the four nucleotides that determine characteristics of organisms. The order in which these nucleotides are stacked and combined creates the diversity in all living organisms. No two sets of DNA are exactly alike. A simple model DNA can be created with pipe cleaners to illustrate this diversity.
Fold each pipe cleaner in half and cut at the fold. Determine what colour will represent each nucleotide. For example, red for adenine, green for thymine, yellow for cytosine and blue for guanine. Adenine can form a pair only with thymine and thymine only with adenine. Cytosine can form a pair only with guanine and guanine only with cytosine.
Fold each of the pieces of pipe cleaners in half. Thread each adenine (red) through a thymine (green) pipe cleaner where they are bent. Hold the open ends of each pipe cleaner and twist to close so the pipe cleaners stay together, leaving ¼ inch of the ends untwisted. Thread each cytosine (yellow) pipe cleaner through a guanine (blue) pipe cleaner. Hold the open ends and twists to close so the pipe cleaners stay together but ¼ inch of each end remains untwisted.
Cut two pieces of yarn 12 inches long. Tie a loop at the top of each piece of yarn large enough to insert a pencil. Lay the two pieces of yarn down on a flat surface so they are parallel to each other and the loops are on the top. Lay the pairs of pipe cleaners between the pieces of yarn to create a ladder pattern. Lay each pair approximately ½ apart vertically on the string. Alternate the pairs randomly so that all 4 nucleotide colours appear on both the left and right side of the ladder rungs.
Twist the ends of the pipe cleaners around the string to hold in place. Glue if necessary. Set aside to dry. Turn the shoebox on its side so that the long side is vertical. Cut off the small side that is facing up. Insert a pencil into the loops at the top of the DNA model. Hold the DNA model up by the pencil. Tape the other ends of the yarn to side opposite the side that was cut off. This end of the DNA strand should be securely taped so it won’t move. Twist the pencil 3 complete turns and set the pencil across the open top of the box.
Create a label on the outside of the box for each colour of pipe cleaner. Write the name of the nucleotide and glue or tape an example of the appropriate colour pipe cleaner next to the name.
Cut small triangles or half circles out of the top edges of the box if necessary to keep the pencil from rolling off.