Building a model of a DNA helix in class will help students visualize DNA's construction and learn about the life-giving genetic code. Using some simple items like toothpicks, plastic foam balls, craft paint and pipe cleaners, you can represent all of the parts that make a DNA helix in a classroom setting. With two colors of balls representing the sugar and phosphate components of DNA and four colors of pipe cleaners representing the four base codes of DNA, you can quickly and easily assemble your model.
Paint 16 plastic foam balls yellow and 18 plastic foam balls red. Choose balls that are approximately 1 to 2 inches in diameter. The yellow balls will represent the phosphate component and the red balls will represent the sugar component of DNA.
Attach nine red plastic foam balls to eight yellow plastic foam balls in a zigzag pattern using the double pointed toothpicks, alternating the colors. Make two lines in this fashion.
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Lay the two lines side by side.
Twist the blue and green pipe cleaners together in pairs and twist the purple and orange pipe cleaners together in pairs. You should have eight blue and green stems and eight purple and orange stems representing the DNA's nitrogenous bases. The blue and green stems represent adenine and thymine, and the purple and orange stems represent cytosine and guanine.
Build a ladder using the lines of balls as the sides and the pipe cleaners as the steps.
Penetrate each pair of sugars (the red balls) with a pipe cleaner stem, using the pipe cleaner stem to attach the sides of the ladder. Continue connecting pipe cleaner stems to each sugar pair down the ladder until you have connected all sugar pairs to pipe cleaner stems.
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The stems can be placed in any order; you do not have to alternate blue and green stems with purple and orange stems.