E55-2009 practice exam 1

Based just on this information the blastula stage

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frog embryo, it contributes to the embryonic kidney. Based just on this information , the blastula-stage tissue would be described as: A. specified B. determined C. differentiated D. both A and B E. none of the above ______20. Depletion of Ca +2 ions in seawater will deter sea urchin fertilization by interfering with: A. Ca +2 flux in the egg B. sperm chemoattraction with resact molecules C. jelly coat production D. the slow block to polyspermy E. phospholipase C activity
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E-55, Exam 1-2009: Name Page 5 of 9 Short answer (point values indicated) . Provide a concise response in the space provided. 21. (8 points) To monitor how the vertebrate spinal cord (a tube) forms from a flat sheet of ectoderm precursors, you decide to use a transgenic reporter strategy in zebrafish. You isolate a 1.5 kilobase (kb) fragment of genomic DNA that is located directly upstream of the first exon encoding a novel gene that is highly and specifically expressed in all ectoderm precursors. A. What reporter gene would let you visualize spinal cord formation in real-developmental time ? Explain why. B. A member of your lab has recently found a zebrafish protein that emits a red color when it is expressed in cells. Would this be useful as a reporter gene in zebrafish? Explain why/why not. C. When you make your transgenic model, you are surprised to find ectopic expression of the reporter in the zebrafish kidney (a mesoderm derivative). In addition, while most of the spinal cord has reporter expression, a region in the tail of the zebrafish is missing spinal cord labeling. Provide and explain a reasonable hypothesis to account for the ectopic misexpression of the reporter and the missing spinal cord expression. 22. (4 points) In fertilization, a sperm enables the egg to become a viable zygote with several actions. List the 3 crucial contributions and/or functions that the sperm from a diploid organism will provide to the egg cell upon fertilization: 1. 2. 3. In contrast, list one sperm component that does not significantly contribute to the zygote: 4.
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E-55, Exam 1-2009: Name Page 6 of 9 23. (4 points) Name 2 important properties of the mouse inner cell mass (ICM) that allows for its use to create a designer mutation: 1. 2. 24. (10 points) Maternal effect genes play a role in the development of numerous embryos, ranging from flies to vertebrates like the zebrafish. A. What is a maternal effect gene, and why have paternal effect genes not been identified? B. You discover a maternal effect gene required for pattern formation of the fly larva body, and you want to assess whether this same gene also patterns the fish embryo body plan. Can you use a morpholino to test a maternal effect gene’s function in the fish embryo? Explain why or why not, and be specific in your response. C. You want to use the zebrafish to find vertebrate-specific factors that are needed for body plan formation prior to the midblastula transition. Clearly outline the screen strategy to accomplish this goal. In your screen diagram, clearly indicate which generation would be examined to find recessive alleles .
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E-55, Exam 1-2009: Name Page 7 of 9 25. (4 points) You make a mouse knock-out model of a transcription factor that is expressed in skeletal muscle progenitor cells. Your homozygote knock-out mice display
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