5. Answer any four of the following five short questions (each question is worth 25 Marks): (a) About 95% of human pre-mRNAs encode more than one protein through regulation of gene expression. Briefly explain how this might occur using an example to demonstrate. (b) Outline how piwiRNAs act to allow the post-transcriptional modification of rRNAs (c) Explain how plasmid addiction systems work to prevent plasmid loss (d) Compare the advantages and disadvantages of random priming versus end labelling as a mechanism of labelling probes (primers). (e) Describe any three different reporter genes used to detect promoter activity in plasmids
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28. Imagine that you discovered a protein, which affects expression of several genes expressed in the Drosophila embryo. You want to test the hypothesis that this protein is a morphogen. Which approach should you use? A. Express your protein in bacteria and test expression of bacterial genes B. Express your protein in Drosophila cells and test expression of fly genes C. Incubate fly embryos with increasing concentrations of the protein and observe if its function is concentration-dependent D. Delete your protein in Drosophila and test expression of fly genes E. Delete your protein in bacteria and test expression of bacterial genes 29. ATAC-seq is a method to measure DNA accessibility. It relies on in vitro integration of engineered Tn5 transposons, which upon insertion lead to DNA fragmentation. Fragmented DNA is then a good material for high throughput sequencing. Eukaryotic gene promoters are often nucleosome-free. What is the most likely impact of nucleosome-free regions on Tn5 integrations? A. Tn5 integrations are not affected by nucleosome-free regions of gene promoters B. Tn5 integrations are enriched within nucleosome-free regions of gene promoters C. Tn5 integrations are depleted within nucleosome-free regions of gene promoters D. None of the above scenarios is likely E. Scenarios A, B and C are equally likely 30. Obtaining plants resistant to a broad-spectrum herbicide is a common application of genetic engineering. Imagine that you took seeds of a non-GMO variety of maize and subjected them to gamma ray irradiation followed by selection with increasing concentrations of a herbicide in an in vitro culture. Among the obtained plants you identified one, which was significantly more resistant to the herbicide than the original plants and this trait was transmitted to the following generations. Is this newly obtained plant strain going to be considered as genetically modified? A. Yes, because its genome sequence has been changed B. Yes, because its DNA has been changed in a way, which can alter functioning of the plant in unpredictable and harmful ways C. Yes, because the same effect could be obtained using genetic engineering D. No, because no genetic engineering has been used E. No, because the DNA sequence has not been changed 31. Genetically modified Cassava plants are resistant to the Cassava brown streak virus because A. They express a protein receptor that recognizes the virus B. They express double stranded RNA complementary to the viral RNA C. They express single stranded mRNA encoding a viral protein D. They express an inhibitor of virus translation E. They express an inhibitor of virus assembly
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Sample questions for Exam III 1) RNAi can work through deadenylation T/F 2) You want to perform a global RNAi screen to identify all of the host cell genes that normally promote microbial growth. So, you transfect human cells with siRNAs and then infect them with your microbe expressing the green fluorescent protein. You should look for: a) increased fluorescence b) decreased fluorescence 3) Interactions involving rRNA are a key part of ribosome function T/F 4) Snurps are primarily found in the cytoplasm T/F 5) TATA-binding protein (TBP) is required for initiation by A) RNA polymerases I, II, and III B) RNA polymerases I and III C) RNA polymerase II D) RNA polymerase III E) RNA polymerase I 6) Methylation of a CpG island in a promoter would a) inhibit gene expression b) activate gene expression c) have no effect 7) An enhancer __________ the gene it affects. A) must be upstream from B) can be very distant from C) cannot be within an intron of D) must be in the same orientation as E) must be downstream from 8) the -10 and -35 elements are spatially conserved between prokaryotes and eukaryotes T/F
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1) Which level of gene expression is most regulated in prokaryotes? a) Transcription b) Post-translational modification c) Translation d) RNA processing 2) Which of the following are found in the lac operon sequence? a) lac Z gene b) lac Y gene c) lac I gene d) lac promoter e) operator sequence 3) Which of the following statements about B-galactosidase is true? a) B-galactosidase is produced when lactose is present b) B-galactosidase creates allolactose from glucose c) B-galactosidase cleaves lactose into galactose and glucose d) B-galactosidase is made from the lac Y gene 4) The lac operon will only be transcribed if glucose is absent. True False 5) The lac repressor... a) blocks B-galactosidase from binding to the promoter b) is always made c) is inactivated by allolactose d) binds to the lac operator sequence 6) Which of the following determines if the lac repressor blocks RNA polymerase? a) The presence of sucrose b) The presence of glucose c) The presence of maltose d) The presence of lactose 7) cAMP... a) helps increase transcription of the lac operon b) is made if glucose is present c) is made if glucose is absent d) binds to CAP protein 8) Which of the following would prevent transcription of the lac operon? a) Neither glucose nor lactose are present b) Lactose is present, but glucose is not c) Glucose and lactose are present d) Glucose is present, but lactose is not 9) Which of the following must be true when lactose is absent but glucose is present? a) The lac repressor is bound to allolactose b) B-galactosidase is produced c) cAMP is made d) The lac repressor is bound to the operator e) RNA polymerase is bound to the promoter 10) Which of the following must be true when lactose and glucose are present? a) The lac repressor is bound to the operator b) cAMP is made c) The lac repressor is bound to allolactose d) RNA polymerase is bound to the promoter e) B-galactosidase is produced 11) miRNAs... a) can lead to blockage of translation for an mRNA b) can lead to destruction of an mRNA c) are made by dicer chopping up a large stretch of dsRNA to form smaller stretches of dsRNA d) block mRNAs from their own genes 12) Nucleosomes contain a) H1 linker b) histone octamer c) DNA Polymerase d) RNA e) histone hexamer f) DNA 13) Control elements include... a) promoters b) proximal control elements c) transcription factors d) enhancers e) RNA polymerase 14) Acetylation of histones leads to a) a more open structure of chromatin b) decreased transcription c) increased transcription d) a more closed structure of chromatin 15) Which of the following help to regulate gene expression in eukaryotes by affecting whether or not transcription may occur? a) transcription factors b) siRNA c) enhancers d) DNA methylation e) histone acetylation 16) Which of the following help to regulate gene expression in eukaryotes by directly affecting whether or not translation may occur? a) siRNA b) histone acetylation c) transcription factors d) enhancers e) DNA methylation
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