Celebrate Rosalind Franklin’s findings by re-creating the DNA shape in this lesson.
Age Level: 13 and up
- 12 toothpicks
- Colored marshmallows or other soft candy (9 green, 9 pink, 9 yellow, 9 orange)
- 2 sticks of licorice
DNA, or deoxyribonucleic acid, is a chemical structure that determines how all living things will look like and function. A genome is an organism’s complete set of genetic instructions. Genes are tiny segments of those instructions to make a protein, which determines specific things such as eye color. A single molecule of DNA looks like a twisted ladder, known as a double helix. The double helix is made up of four amino acids called adenine, thymine, cytosine, and guanine. In a DNA strand adenine and thymine, and cytosine and guanine always pair together.
- Gather your materials. The marshmallows represent the different amino acids in DNA: (A) adenine is green, (T) thymine is pink, (C) cytosine is yellow, and (G) guanine is orange.
- Pick one of the two sequences for your DNA.
Sequence 1: TCATGAAACTTA
Sequence 2: TTGACATAGTAG
- Determine your DNA sequence. A piece of DNA is made up of two sequences that complement each other. (A) always pairs with (T) and (C) always pairs with (G). If your first strand is TAGC, then your second strand will be ATCG. What is the complementary sequence for GATC? __ __ __ __
- Each color of marshmallow should correspond with your DNA strands. For example, if your first three amino acids are TCAG, then your marshmallow order should be pink, yellow, green, and orange. Take a stick of licorice and place it on a flat surface. Then place your first marshmallow next to the licorice. Take a toothpick and stick it through the marshmallow and the licorice. Repeat with a second stick of licorice to correspond with the first strand.
- Now, connect both strands by pushing the marshmallows through the opposite toothpicks. Once the strand is assembled, it should look a lot like a ladder and be flexible. Twist it slightly so that you can see the DNA double helix strand!
- Share your DNA with us by taking a photo and tagging us at @imasmuseum Instagram and Twitter or @imasmcallen on Facebook. Continue learning about influential women scientists at the Story Collider Podcast, a podcast that tells the story of scientists, engineers and doctors from all over the world.
Image Credits: Creative Commons
Cited: Maxmen, A. 2018. Why it’s hard to prove gender discrimination in science. Nature. https://doi.org/10.1038/d41586-018-05109-w