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Biology LibreTexts

3.E: Cleavage and Gastrulation (Exercises)

  • Page ID
    21098
  • At-home assignment

    Make an illustration (by hand or computer-aided) for one of the topics/concepts we covered this week. Please cite your sources.

    Group assignment

    Choose a Bicoid model to explain to the class. Your explanation should include:

    1) The location of mRNA and protein in the embryo

    2) Any factors that impact the location of mRNA and protein (e.g. degradation)

    3) How this model could be used to explain scaling in higher Dipterans (i.e. how can you use this model to build a small or a large embryo?)

    4) How the model was tested and whether it held up to the test

    5) BONUS: other experiments that researchers could run to test the model and what their results would tell us.

    Discussion Questions and Reading Guide

    The questions below were originally written for students reading Freaks Of Nature by Mark Blumberg and Endless Forms by Sean Carroll. However, the questions in bold are discussion questions that can be answered without these books.

    The "Reading Guide" questions are appropriate for short homework answers and the "Discussion Guide" questions are appropriate for open in-class or online discussion.

    Chapter 2 and 3 of Endless Forms

    Reading Guide

    1. What is a morphogen? Give examples
    2. What is a homeotic change?
    3. What is polydactyly? Is it a homeotic change?
    4. How does the lac-z operon help explain cell-type differentiation?
    5. What is the central dogma of molecular biology? At which step is the lac-z operon regulated?
    6. What are the two features of gene logic in bacteria?
    7. What is a homeobox and how does it relate to homeotic transformations?
    8. Homeoboxes are incredibly conserved between disparate animal species, what kind of selection is this?
    9. What is a conserved function of Pax-6 genes?
    10. What does the Distalless gene do in general?
    11. What does the tinman gene do in general?

    Discussion Guide

    1. What experiments showed that the "dorsal lip of the blastopore" acts as an organizer tissue?
    2. What are the general properties of an organizer?
    3. Freaks discussed the importance of environment and plasticity in Chapters 1 and 2, how does Endless Forms' discussion of hopeful monsters contrast with this?
    4. In homeotic fly mutants, the antennae/wing look fairly normal - why is it that we recognize them as normal structures in the wrong place?
    5. How do cells get differentiated and why is it important?
    6. Explain the lac-z operon using the terms "cis" and "trans"
    7. What did Monod mean when he said "What is true for E. coli is also true for the elephant."?
    8. What are some similarities between building a fruit fly and building a human?
    9. What is similar between Tinman, Pax6, Dll, and Hox genes?
    10. What is the "genetic toolkit" and what are it's implications for evolution?