Wednesday, April 4, 2012

Getting a glimpse of our genetic ghosts: A day of science outreach

Last spring, I participated in Yale’s Science Education Outreach Program (SEOP). We traveled to middle schools around New Haven and Fairfield, CT with the aim to excite children about science by teaching fun, hands-on biology lessons.

A class of twenty-seven regards me with mild curiosity. In the back a few girls are speaking in what barely qualifies as a whisper. One boy feints a punch at his neighbor.

To my left is a model of DNA we have assembled for the class, neatly displaying the pairing of nucleotides- always Adenine (A) with Thymine (T), and Guanine (G) with Cytosine (C). You can clearly see the sugar and phosphate backbone that makes the outer rails of the helix twisting around the nucleotide steps. The whole thing looks like the colored spiral staircase of a children’s show. 

“I need a volunteer! You look like a DNA specialist! Could you come help me read the DNA?”

A small girl of about 12 lopes up to the front of the room, the beads in her braided hair flashing excitedly in the afternoon sunlight. She helps me read the DNA staircase top to bottom, and I record her oration on the whiteboard with a cherry red pen.

“A, G, G, T, C, C, G, A, C!”

After thanking my assistant, I draw a sun on the board, and then a jagged beam extending from its surface to the unsuspecting Thymine in our sequence of nucleotides.

“You know how adults always tell you to put on sunblock before you go play in the sun? The sun actually sends out tiny little particles, called ultraviolet rays, that hit your body. When these rays hit your DNA, they can hurt the DNA and cause a mutation. Mutations are when DNA is changed, like making this T into a G.  If you get enough mutations in parts of DNA that control the growth of your body, a small part of your body can grow uncontrollably. This is called cancer.”

The eighth graders look mildly alarmed, but interested. No one speaks, no one texts.

“So, would you like to see what your very own DNA looks like?”

Heads nod with enthusiasm; one boy throws up his hand.

My partner, a vigorously healthy cell biologist, begins to distribute small paper cups holding 6 milliliters, or a little more than a teaspoon, of water. I follow him, passing out wooden stir sticks, our two heads bobbing through the aisles like ducks on a pond. We have both played the role of speaker and assistant over the last several weeks, and so have we learned to complement each other in the classroom. He grins wryly as he hands me my own cup when we circle back to the front of the room.

“All right everyone! To get our DNA, we first have to get some cells! The inside of your mouth is covered in a lot of loose cells that are constantly replacing themselves. We are going to collect some of those cells, break them open, and get out your DNA that is packed inside! 

You know how you have feet and feet of intestines in your belly? Your DNA is very very tightly packed in your cells, kind of like your intestines. Opening up even a few cells can give you lots of DNA.

First you are going to scrape the inside of your cheek with the wooden stick, like this. Don’t do it too hard, but the longer you scrape the more cells will come loose, and the more DNA you will get. Then you will swish the water in your mouth, like a mouthwash commercial, and spit it back into the cup.”

I demonstrate, shameless in the pursuit of education, and I hear a few breaking voices express amused disgust. They follow my lead, scraping and then washing away the taste of pine with the light, flavorless Evian. My partner passes out capped plastic tubes half-filled with soapy salt water.

“Ok, our friend just handed you a tube of soapy water. This soap will help break open your cells. What you are going to do is pour your water into the tube, close it firmly, like this, and slowly turn the tube upside down and back again, over and over, for a minute. My favorite way to do this is make it a dance.”

I take my tube, now filled with mouth cells and soapy water, and arc my hands side to side in an extremely inept but humorous dance move. And twenty-three students do the same. While they jive to science, my partner and I grab ice-cold ethyl alcohol, and pick up transfer pipettes that resemble teaspoon-sized turkey basters. We trace the room again, dropping 1 milliliter of alcohol into each student’s tube, asking them to hold it sill and watch the layer of alcohol that floats above the soapy water.

After a moment, white swirls appear in the clear, cold alcohol at the top of each tube. These ethanol-surrounded ghosts, our DNA, code for everything in our body. Even now, after years in a laboratory, I find its beauty haunting.

My partner and I have the children come to us in groups, and we suck up their DNA with transfer pipettes. We then squeeze out their DNA into little colored tubes, green for one, an ambiguous pink for another. We attach these tubes to a piece of short twine, and the students hurriedly affix their DNA ‘bracelets’ to wrists, ankles, backpacks and belt loops.

They are smiling.

-Katherine Mahala Burn
5th year Cell Biology graduate student