Corn taco

The Case of the “Tainted” Taco Shells
Advanced Biochemistry Edition

by
Ann Taylor
Department of Chemistry
Wabash College


Part I—Taco Night

“Hi, Dad, I’m home! Can Chris join us for supper?” Mark asked as he walked into the kitchen. “Practice ran over and he’s got to go straight to the fields and help his dad, but there’s always time for taco night, right?”

Dad lifted his head from the newspaper. “Only if he likes tacos without the shells. Hi, Chris. Got a date for the prom yet?”

“Nope. Still looking, Mr. Schumer.”

Dad continued, “I went to Kroger today, and all of the Taco Bell shells were gone. The cashier said there was some sort of recall. And you know your sister can’t have the flour ones because of her wheat allergy.”

“Well, we’ve got some hot dog buns, so let’s imp-ro-vise!” Mark said with a flourish. “What’s up with the recall? I thought that only happened with bad hamburger?”

Dad folded the paper over and pointed to a headline. “It’s all in the genes. This article says the shells accidentally contained some genetically modified corn called StarLink. StarLink is a feed corn, but it isn’t approved for human consumption.”

“So the cows can eat it, but we can’t? That doesn’t make sense,” said Mark.

Chris jumped in. “StarLink hasn’t been proven to be safe for humans to eat—you know, not toxic or allergenic. That’s important, especially to your sister.”

“What’s important to me?” asked Michelle as she walked in and sat at the table. “Hi, Chris.”

“Oh…. Hey, Michelle.” Chris was blushing. “We were just talking about, um, taco shells.”

Mark rolled his eyes.

Dad turned to Chris. “Chris, your family farms corn, right?”

“Right.”

“Well, why would your dad want to grow genetically modified corn?”

“Do you remember the year Mark helped us detassle?” Chris asked.

Mark winced. “That was the worst job ever. My hands felt like they were at a paper cut convention!”

“That was the easy part.” Chris said. “What if you had to walk the fields twice a year and pull all the weeds? That’s what my dad had to do when he was a kid. Now he uses Roundup spray and Roundup Ready seeds. He sprays the field once and all the weeds die. But the crop is okay because the seeds have been genetically modified so the plants won’t be affected. The only bad thing is that the seeds are a little more expensive and you have to buy the spray, but it is still a lot cheaper than weeding by hand.”

“And my hands, thank you,” Mark said, waving his hands and bowing.

Chris ignored Mark and continued. “My dad uses another seed that is resistant to insects. When I was ten, we almost lost the entire crop to corn borers, so Dad was pretty happy when this seed came out.”

“So how does it work?” Michelle asked, smiling.

“Well,” said Chris, his face still a little pink. “All I know is from talking to the seed salesman. He said the corn produces a bacterial protein that is toxic to insects. So when a bug chews on the plant, it dies.”

Michelle frowned. “Bacteria? You mean they’re loading up my food with extra chemicals and toxic proteins just to make life easier for farmers?”

“Wait a minute. Farming isn’t easy, Michelle. My dad had to get a second job just to keep the farm that’s been in our family for three generations!”

“Well, what about the butterflies?” Michelle asked, setting her jaw. “They’re related to corn borers. Are they killing them, too?”

“I don’t know, Michelle.” Chris was getting defensive. “Besides, what does that matter? Butterflies don’t eat corn!”

“But I do!” Michelle sputtered. “And I’m not gonna eat any of this Franken-Food if I can help it!”

Mark stuck his arms forward and wobbled around. “Igor, it’s alive! ALIVE!”

Dad looked up again. “Mark, grow up. Michelle, calm down. This could be a good thing. There’s another article in here about a company that is genetically modifying rice to include vitamin A. They think it will greatly reduce childhood blindness in developing countries.”

“That’s great,” Mark said, “but with all this modification and insect resistance I wonder what happens if the weeds become resistant to the Roundup?”

“Good question,” said Dad. “Let’s continue this over dinner. Mark, sit over here. Chris, why don’t you sit by Michelle.”

Questions

  1. How is genetically modified corn made and detected?
  2. How do genetic modifications give plants insect and herbicide resistance?
  3. Is genetically modified corn safe?
  4. Can farmers make a living without it?
  5. Will Chris ask Michelle to the prom?

Go to Part II—“Project Design”


Date Posted: 03/17/04 nas

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