I’m out of town! Class is canceled today! But still, my cold grip extends across the Cascades, over the Palouse, the Rockies, the Dakota badlands, the old homeland of the American bison, the the great farms of the midwestern heartland, to a small town in western Minnesota, where I crack the whip over a tiny group of hardworking students. They’ve been mastering the basics of timelapse video microscopy in the lab this week, I hope, and will be showing me the fruits of their labors on Monday. I’m also inflicting yet another exam on them over the weekend. Here are the questions they are expected to address.
Developmental Biology Exam #2
This is a take-home exam. You are free and even encouraged to discuss these questions with your fellow students, but please write your answers independently — I want to hear your voice in your essays. Also note that you are UMM students, and so I have the highest expectations for the quality of your writing, and I will be grading you on grammar and spelling and clarity of expression as well as the content of your essays and your understanding of the concepts.
Answer two of the following three questions, 500-1000 words each. Do not retype the questions into your essay; if I can’t tell which one you’re answering from the story you’re telling, you’re doing it wrong. Include a word count in the top right corner of each of the two essays, and your name in the top left corner of each page. This assignment is due in class on Monday, and there will be a penalty for late submissions.
Question 1: One of the claims of evo devo is that mutations in the regulatory regions of genes are more important in the evolution of form in multicellular organisms than mutations in the coding regions of genes. We’ve discussed examples of both kinds of mutations, but that’s a quantitative claim that won’t be settled by dueling anecdotes. Pretend you’ve been given a huge budget by NSF to test the idea, and design an evodevo research program that would resolve the issue for some specific set of species.
Question 2: Every generation seems to describe the role of genes with a metaphor comparing it to some other technology: it’s a factory for making proteins, or it’s a blueprint, or it’s a recipe. Carroll’s book, Endless Forms Most Beautiful, describes the toolbox genes in terms of “genetic circuitry”, “boolean logic”, “switches and logic gates” — he’s clearly using modern computer technology as his metaphor of choice. Summarize how the genome works using this metaphor, as he does. However, also be aware that it is a metaphor, and no metaphor is perfect: tell me how it might mislead us, too.
Question 3: We went over the experiment to test the role of enhancers of the Prx1 locus which showed their role in regulating limb length in bats and mice. Explain it again, going over the details of the experiment, the results, and the interpretation…but without using any scientific jargon. If you do use any jargon (like “locus”, “regulation”, “enhancer”), you must also define it in simple English. Make the story comprehensible to a non-biologist!
Yeah, you don’t have to tell me. I’m evil.