How to Make a 3-D DNA Model Structure

You can easily make a DNA model.

Deoxyribonucleic acid (DNA) is the basic building pattern for all life, plant and animal. The double helix formation of bases in the center and sugar-phosphate along the edge provides the mechanism for passing traits from parent to child. Four bases combine. Thymine and adenine always combine while cytosine and guanine always combine. The order in which these bases appears on the string of DNA determines the specific characteristics of the organism. A 3-D model will show these combinations and the phosphate/sugar combination along the sides of the DNA ladder.

Things You'll Need

• Craft wire
• Scissors or wire cutters
• 40 large yellow beads to represent phosphate
• 40 large pink beads to represent sugar
• Thick orange pipe cleaners to represent adenine
• Thick red pipe cleaners to represent thymine
• Thick blue pipe cleaners to represent cytosine
• Thick green pipe cleaners to represent guanine
• Glue
• Shoebox

Instructions

1. Cut two lengths of craft wire 12 inches in length. These will be the supports for the sides of the DNA ladder. Grasp one end of the first wire and curl it into a small circle to prevent the beads from slipping off the wire. String 20 each of the yellow and pink beads, alternating to form a pattern of one yellow on top of one pink bead. There should be a small amount of wire left at the top. Bend this wire into a circle to prevent the beads from slipping off. Carefully set aside and repeat for the second length of wire.

2. Lay the two lengths of beaded wire on a flat surface so they are parallel to each other and 2 inches apart. Cut the pipe cleaners into 2-inch lengths. There should be 20 lengths of each color. Bend each pipe cleaner in half in the middle. Thread each bent orange pipe cleaner through the bent side of each red pipe cleaner to create pairs of adenine and thymine. Grasp the open ends of the joined pipe cleaners and twist until the two colors of pipe cleaners are twisted tightly and form a strong "rung" for the ladder. Keep ¼ inch of the open ends untwisted. Repeat the process with the blue and green pipe cleaners to create the cytosine and guanine rungs for the DNA ladder.

3. Place the pipe cleaner rungs of the ladder between the two beaded wires. The rungs will attach just above each pink bead. The pattern of colors on the rungs can be random, with all four colors appearing on both the right and left sides of the rung. Twist the open end of each pipe cleaner around the wire above each pink bead. Add a drop of glue to secure the pipe cleaners to the wire. Add a drop of glue above the top bead and below the bottom bead on the wire so they will not move. Set aside to dry overnight.

4. Uncurl the wire at the top of the DNA ladder. Set the shoebox so the long side is vertical. Insert the uncurled wire from the inside toward the outside of the box on the side facing up. Bend the wire on the outside of the box. Add a drop of glue to hold it in place. Unbend the unbeaded wire at the bottom of the DNA string. Grasp the bottom of the DNA ladder and twist at least twice in a complete circle to create the double helix shape of DNA. Insert this wire through the bottom of the shoebox to the outside. Bend the wire. Add a drop of glue to hold it in place. Allow the glue to dry before setting the shoebox back up.

References

• Biology Online: DNA
• Estrella Mountain Community College: DNA