Exam 1 ID#: October 16, 2007

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1 Biology 4361 Name: KEY Exam 1 ID#: October 16, 2007 Multiple choice (one point each; indicate the best answer) 1. After searches by many embryologists, the mammalian egg was finally discovered by a. William Harvey b. Karl Ernst von Baer c. Marcello Malpighi d. Kaspar Friedrich Wolff 2. Which of the following agrees with von Baer s laws: a. The embryos of mammalian species resemble adult stages of amphibian species. b. General features appear earlier in development than do specialized features. c. both agree d. both disagree 3. The epigenetic theory of development a. required the growth of new structures during development. b. explained the mixture of traits in hybrids. c. was hampered by the perceived need for a vital force. d. all of the above. 4. Diploblastic animals lack a. mesoderm b. endoderm c. ectoderm d. germinal epithelium 5. A fate map a. determines whether a particular blastomere will survive. b. predicts the point at which a cell will move to a new location. c. tracks the differentiation pathway for a cell or group of cells. d. tracks the movement of stem cells through differentiation. 6. Cleavage can be described as a. increase in cell number, but no cell growth. b. cell growth, but no increase in cell number. c. nuclear division without cytoplasmic division. d. cytoplasmic division without nuclear division. 7. Transplantation of tissue from one embryo to another of a different species is called: a. heterospecific b. heterochronic c. homospecific d. homochronic 1

2 8. Embryonic cells that change fates to compensate for cells that have been removed from the embryo demonstrate a. regulative development. b. unregulated development. c. variable development. d. invariant development. 9. In organisms with autonomous specification the distribution of determines cell fate. a. egg cytoplasm b. maternal RNA c. egg proteins d. all of the above 10. You discover a Drosophila embryo with no apparent head, but with tails at both ends. A plausible explanation is a mutation that inactivated the gene. a. nanos b. bicoid c. Pax6 d. distal-less 11. Cell-cell adhesion is often mediated by a. carbohydrates b. cadherins c. catenins d. all of the above 12. RNA interference pathways probably evolved in response to a. hybridization. b. cross fertilization. c. double stranded RNA viruses. d. double stranded DNA viruses. 13. Inserting a donor nucleus into an enucleated egg a. provides the genetic material. b. provides the genetic material and activates the egg. c. provides the genetic material, activates the egg, and starts the process of nuclear fusion. d. none of the above. 14. Natural genetically coded short RNA sequences that form stem-loop structures are called a. sirna b. microrna c. isrna d. mtrna 2

3 15. Histone acetylation gene transcription. a. allows b. slows c. inhibits d. none of the above 16. Enhancers differ from promoters in that they a. are made of proteins. b. must operate in close proximity with the transcription start site. c. can bind a variety of proteins. d. can operate in a reverse orientation. 17. Messenger RNA in a particular set of cells or tissues can be analyzed using a. DNA microarrays. b. DNA macroarrays. c. in-situ hybridization. d. all of the above. 18. TFIID, TFIIB, and TFIIA a. bind to the core promoter. b. form a portion of the transcription initiation complex. c. bind RNA polymerase II. d. all of the above. 19. DNA methylation patterns are a. destroyed during replication and must be reformed after mitosis. b. enzymatically maintained during replication and division. c. permanent once the nucelotides are initially methylated. d. highly variable throughout replication and division. 20. When a Dictyostelium pseudoplasmodium is cut in half some of the posterior cells, which were fated to become spores, now become pre-stalk cells. This demonstrates a. determinative development. b. autonomous development. c. mosaic development. d. regulative development. 3

4 True / False (1 point each) 21. The first observable cellular activity in the oocyte after fertilization is cytoplasmic rearrangement. True / False 22. Histone methylation represses transcription. True / False 23. Cytosine methylation represses transcription. True / False 24. Muscles and bones are generally derived from mesoderm. True / False 25. An insect blastoderm is homologous to a mammalian blastocoel. True / False 26. In Drosophila the syncytial blastoderm stage is followed by the cellular blastoderm stage. True / False 27. In protostomes the mouth originates from the blastopore. True / False 28. Dosage compensation refers to techniques that adjust the level of antibiotic resistance genes in knockout experiments. True / False 29. Heterochromatin forms the light bands seen in polytene chromosomes. True / False 30. Nuclear hormone receptors are a sub-family of transcription factors. True / False 31. Enhancers can be located next to an exon. True / False 32. More than one system of specification can be seen in some species. True / False 4

5 Fill in. (1 point per answer) Use the terms from the Term Bank to make the most accurate sentence. Term Bank antibiotic resistance basal transcription factor(s) blast cellular blastoderm chiasmata chimera cis acting committed stem cells dermal Dicer dimers fate histone acetyltransferase histone deacetylase hormones methylase monomers mosaic phosphodiesterase morphogen pleiotropy pluripotent stem cells potency protein-protein interaction domain RISC syncytium TATA box trans acting transfection transposable elements 33. The term blast refers to cells or tissues that make up formative units of living matter. 34. A cell undergoing nuclear division without cell division is referred to as a syncytium. 35. The enzyme histone acetyltransferase is associated with transcriptional activation. 36. RNA polymerase II must have both the basal transcription factor(s) and the TATA box to transcribe genes 37. Enhancers are considered cis acting regulators, while transcription factors are considered trans acting regulators. 38. Specific transcription factors often form dimers, which bind through their protein-protein interaction domain. 39. As a blastomere develops, its potency generally decreases as it progresses toward its fate. 40. RNAi techniques utilize the cellular enzyme Dicer, which is part of the RISC complex. 41. Foreign genes can be inserted into cells using transfection or transposable elements. 42. Intrauterine factors such as hormones can act to influence development. 43. Committed stem cells can produce committed stem cells but not pluripotent stem cells. 5

6 Short Answer. (5 points each; answer any six. Be certain to address all parts of the questions.) 44. What is meant by a weak promoter? - weak promoter = a promoter that does not support rapid or sustained gene transcription - e.g. poor RNA polymerase II binding - e.g. poor basal transcription factor binding 45. Why are different banding patterns observed in polytene chromosomes at different times during development? - dark bands are areas of heterochromatin = transcriptionally inactive - light bands are areas of euchromatin = transcriptionally active - changing banding patterns indicates that different areas of the gene are becoming active 46.Your experiment to produce transgenic mice resulted in 25% that showed no trace of the transgene trait, 50% that showed partial expression of the trait, and 25% that died before birth. What can you conclude about your gene? - the transgene was incorporated into the primordial germ cells (gamete precursor cells) since the offspring were affected - however, the transgene was lethal in the homozygous condition - your results show a Punnett square distribution with 25% wild type (no effect), 50% heterozygotes (partial effects), and 25% homozygous for the transgene (lethal) 47. When you remove a blastomere from the embryo you are studying, the remaining portion of the embryo develops normally, and a complete (although smaller) organism develops from the single blastomere. What can you say about: A) the type of specification exhibited by this organism. - conditional specification; the remaining blastomeres were able to compensate for the missing cell and produce a complete embryo B) the potency of the blastomere at the time of removal. - the blastomere was either totipotent or pluripotent; the single blastomere was able to produce an entire embryo; if it was from a placental mammal, it may have been a pluripotent inner cell mass blastomere 48. Describe the technique used to create reporter genes, and describe their use. - attach a gene for a reporter molecule (e.g. luciferase, â-galactosyltransferase, fluorescent protein) to the regulatory region of a gene of interest - genes are transfected into cells or organisms; used to detect cells/tissues where gene would be active 49. In an experiment using a model species that undergoes conditional specification you transplant cells that would form the tip of the wing to an area that will form the middle joint of a leg. How would you expect to characterize the resulting transplanted cells? - transplanted cells would be wing-type cells that took the character of mid-wing, instead of tip 6

7 50. Arrange the following gene features in their most common order: upstream promoter region, promoter region, TATA box, transcription initiation site, leader sequence, translation initiation site, leader sequence, exons, introns, translation termination site, polya addition site, transcription termination site - upstream promoter region, promoter region, TATA box, transcription initiation site, leader sequence, translation initiation site, leader sequence, exons, introns, translation termination site, polya addition site, transcription termination site 51. Nuclei from embryonic stem cells can make a new embryo, but are not considered totipotent. Why? - embryonic stem cells cannot form the embryonic trophoblast Short Essay. (10 points each; answer any two. Be certain to address all parts of the questions.) 52. Explain, using the terms specification and determination, how one would perform transplantation experiments to determine the stage of differentiation in developing tissues. - transplanted to neutral areas (or culture dishes) shows whether cells are specified - if they change course or do not progress; they are not specified - if they continue to develop according to their presumed fate, they are specified - transplanted to areas that will develop different fates - if they develop into the new (i.e. host area) fates, they were not committed - if they continue to develop following their original presumed fate, they were committed 7

8 53. Describe the purpose and the method for making chimeric organisms. - purpose - to create a line of animals that contain a transgene - method: - create embryonic stem cells containing 1) a transgene (the target gene) 2) a gene for antibiotic resistance - grow the ES cells in a culture containing an antibiotic (that will kill any cells not containing the gene for antibiotic resistance) - insert the surviving ES cells, which contain the trangene and antibiotic resistance gene into the inner cell mass of a host embryo - implant the gene into the host uterus - resulting mice will be chimeric (containing cells derived from either the host or the transgenic embryo) NOTE - to make transgenic animals, cross chimeras with each other; select animals homozygous for the transgene - requires that transgene ES cells integrate into the reproductive cells (sperm/eggs) of the chimera 54. Describe three ways that gene transcription rates can be regulated; one each at the chromatin level, DNA level, and post-transcriptional processing level. Using a hypothetical gene (one that you make up), describe how a signal (environmental, extracellular, or intracellular) could increase the rate of transcription by operating through one or more of these pathways. Chromatin: histone acetylation/deacetylation; methylation DNA: promoter strength; enhancer/transcription factors; methylation Post-transcriptional: capping, poly(a) addition, splicing Bonus Question (1 pt.) Mario Capecchi, Martin Evans, and Oliver Smithies were awarded the 2007 Nobel Prize in Physiology or Medicine for developing what technique? gene knockouts (transgenics using ES cells) 8