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Direct signaling via proteins that interact between

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B. direct signaling via proteins that interact between the respective cell membranes C. secretion of a morphogen from one cell D. organizer activity in one of the cells E. all of the above are possible ______10. Which of the following does not require you to know the gene you want to study: A. gene knockdown with an antisense technique like RNAi B. gene targeting C. forward genetic screen D. mRNA overexpression using microinjection E. none of the above ______11. Fate mapping in the tunicate embryo shows that 4 blastomeres in the 64-cell-stage blastocyst always give rise to the spinal cord. You remove these 4 blastomeres at the 64- cell-stage and place them into the mesoderm of a gastrula stage tunicate embryo. In this new location, the 4 blastomeres die. What can you deduce about the commitment of the transplanted blastomeres? A. they are differentiated B. they are specified C. they are determined D. they are determined but not yet differentiated E. none of the above ______12. The presence of cytoplasmic bridges characterizes: A. spermatogenesis B. all gametogenesis processes C. oogenesis D. the zygote immediately following sperm entry E. none of the above ______13. Bindin, a protein found in sea urchin sperm, mediates A. binding of the sperm to fertilization envelope B. binding of the sperm to the jelly coat C. binding of the sperm to the cumulus cells D. binding of the sperm to the vitelline envelope E. physical entry of the sperm into the egg cytoplasm ______14. A maternal effect mutation results in phenotypes only when A. the father carries a mutant allele B. the mother carries a mutant allele C. the offspring carry two mutant alleles D. both parents carry mutant alleles E. the offspring have one mutant and one wild-type allele
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E-55, Exam 1-2010: Name Page 4 of 8 ______15. When the sodium concentration in seawater is decreased, the incidence of polyspermy in sea urchin eggs A. is abolished B. is increased C. is decreased D. is unaffected E. is eliminated because sperm swimming is blocked ______16. You treat sea urchin eggs with a phospholipase C inhibitor. Which step in fertilization will be affected? A. sperm binding to the jelly coat B. sperm binding to the vitelline envelope C. the slow block to polyspermy D. fusion of the egg cell membrane with the sperm cell membrane E. none of the above ______17. Egg production involves the accumulation of products to assist the zygote. Which of the following can be found in eggs? A. ribosomes B. mRNAs C. histones D. RNA polymerases E. all of the above ______18. Across metazoans, eggs share which of the following attributes at the time of fertilization? A. a jelly coat surrounding the oocyte B. a layer of somatic cells that surround the oocyte C. a haploid nucleus D. an abundance of dense yolk proteins E. a cell membrane ______19. You wish to visualize pancreas formation in live zebrafish embryos so you decide to make a transgenic fish that expresses GFP in pancreas cells. Transgenic animals are best described as the result of the ______of a piece of DNA that is ______the next generation.
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