10/12/2020
image from: https://www.kjmaclean.com/Geometry/Icosahedron.html
The day my father saw a single stranded DNA helix in his electron microscope was the day his college mounted a brass double-stranded DNA helix model on the wall beside the building where he did his research. His students immediately unscrewed one of the helices from the wall and took it to his office.
That was also the day that my fifth grade teacher asked us to find out the name for a 20-sided shape. I went home and asked my mom. She told me, as she usually did, “look it up.” I tried. We had a dictionary. You can’t look up “20-sided shape” in a dictionary. My grandfather had given us an encyclopedia. You also can’t look up “names for multi-sided shapes” in an encyclopedia. I planned to go to the library the next day. Then my father came home.
He was in a good mood because of the single stranded DNA discovery. He asked what I was looking for in the encyclopedia. He’d just found something that wasn’t in it. I told him I was looking for something that also wasn’t in it. I told him my teacher asked us to find the name for a 20-sided shape. He said, “Icosahedron.” My father was a college professor. If he said that was the name, my teacher should be satisfied. I cancelled my plan to go to the library and look it up.
The next day when I went to 5th grade, I told my teacher that my father had said the name was “icosahedron.” She said that was wrong. “The right name is ‘duodecahedron.’” I couldn’t go home and tell my father that he was wrong, so I didn’t say anything to him. I did check our classroom dictionary. The word icosahedron wasn’t in it. I didn’t tell my teacher that.
A few days later, my father phoned about the time I got home from school. My mother drove to the High V grocery to buy meat. A couple of men named Mr. Watson and Mr. Crick were coming to our house for dinner. No, Mr. Watson didn’t have anything to do with Sherlock Holmes. And Mr. Crick didn’t creak when he walked, but he was much older and grayer than Mr. Watson or my dad. My mom wanted me to leave her alone so she could cook. She wanted to make sure the dinner was good so my dad wouldn’t yell at her in front of the guests. The men were coming to dinner because they were interested in my father’s single stranded DNA. It had something to do with genetics, which was how people inherit looks from their parents. Knowing if it was double stranded, or single stranded, or both was important.
Our dinner guests had math from a scientist named Rosalind Franklin showing that DNA was double stranded. They were publishing a paper about it. They wanted to look at my father’s work to see if it should be included in their paper. Mr. Watson was also interested in my sister’s blue eyes. My mother has green eyes and my father has brown eyes, like my brother and me. He concluded that both of my parents must carry a gene for blue eyes because you can only have blue eyes if both your parents give you a gene for that color. The gene was made of DNA.
The next day, my father took these men to his lab to show them his electron microscope. His DNA was from a virus that grew in the shape of an icosahedron. Theirs was from mammals. I went to school. My teacher said she had looked up “icosahedron.” She had found that it was just as good a name as duodecahedron for a 20-sided shape. Now that we had a name for 20-sided shapes, our 5th grade class made a combined art and math project — building 20-sided shapes to hang from the ceiling of our classroom.
Here’s a video showing how to make an icosahedron. (You don’t have to put the elements on the sides.) https://www.youtube.com/watch?v=2KyJ1TI6V7E
