E55-2010 exam 2

E 55 exam 2 2010 name page 5 of 8 short answer point

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E-55, Exam 2-2010: Name Page 5 of 8 Short answer (point values indicated). Provide a concise response in the space provided. 21. (10 points, 2 points each) Axis specification is an important event during early embryogenesis. A. In the fly, which axis is established first? Circle your response: A-P D-V L-R B. In the fly, name the protein that the oocyte produces that is essential for setting up both the A-P and D-V axes? __________________________________________ C. If you were to prevent microtubule polymerization in the fly oocyte, which axis or axes would be specified? Justify your response in 1-2 sentences. D. In the frog, which axis is established first? Circle your response: A-P D-V L-R E. If you were to prevent microtubule polymerization in the frog zygote, what phenotype would result? (Hint: we are looking for the one-word description of phenotype) __________________________________________ 22. (6 points) A 1-cell stage frog zygote is incubated with a drug that degrades B- catenin molecules. 1. Will the embryo be able to produce ventral tissues? Circle your response: yes no 2. Will the embryo be able to produce neural tissues? Circle your response: yes no 3. Will the embryo be able to make an organizer? Circle your response: yes no
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E-55, Exam 2-2010: Name Page 6 of 8 23. (10 points, 2 points each) During early cleavage, a period of extremely rapid cell division occurs in most vertebrate embryos. A. What stages of the cell cycle occur during the rapid cell division period? ______________________________________________ B. What are the two molecular components of the MPF complex? 1 ________________________________________ 2 ________________________________________ C. Which of the molecular components is degraded with each cell cycle? ________________________________________________ After the rapid period of cell division, there is a switch to a slower period of cleavage cell division. What name is given to this switch, and what new molecular event commences in each cell at the time of this switch? D. Name:________________________________________ E. Briefly describe the new molecular event in embryo cells (short phrase or 1-2 sentences only): 24. (6 points, 2 points each) Cells move in a variety of ways during development. A. Define intercalation in a short phrase: B. Intercalation can contribute to two other types of cell rearrangements. Name them: ________________________________________________ ________________________________________________
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E-55, Exam 2-2010: Name Page 7 of 8 25. (10 points, 2 points each) You isolate mesoderm and endoderm from a late-stage blastula frog embryo, dissociate the cells from their neighbors, and then put them in culture as a random mass of mixed mesoderm and endoderm cells.
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E 55 Exam 2 2010 Name Page 5 of 8 Short answer point values...

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