a A b B c C d D e E BSCI330 Fall 2012 Exam II KEY Part I Multiple Choice 1 5 pts each 1 Which of the following is true about the mechanisms of genetic information flow in eukaryotic cells but NOT prokaryotic cells a The direction of information flow is DNA RNA protein b Regulation occurs at both transcriptional and post transcriptional stages c RNA splicing removes intron sequences from pre mRNA d Protein translation starts by using a special initiator methionine tRNA 2 Which among the following arrangements in the figure below is LEAST likely to occur Extracellular space intracellular space 3 Which of the proteins in the image above question 2 would be extractable from a membrane with a high salt solution a A B and C b B only c E only d C and D e B and E f All proteins depicted could be extractable with high salt solution 4 Which of the following accurately describes the acetylcholine receptor at neuromuscular junctions a b c d It is a voltage gated cation channel It is a P type Ca2 pump It is a mechanosensitive ion channel It is a ligand gated cation channel 5 Which of the following describes a function of the 7 methylguanosine cap a Helps the cell to distinguish mRNA from rRNA b Prevents mRNA degradation in the cytosol c Serves as a ribosome binding site to initiate translation d All of the above e None of the above Last Name 1 BSCI330 Fall 2012 Exam II KEY 6 Which of the following is true about eukaryotic RNA polymerase II It requires general transcription factors to help position it on DNA during initiation It is involved in the transcription of ribosomal RNA It adds a poly A tail to RNA after transcription is complete a b c d All of the above e None of the above 7 Which of the following is a property of enhancers but NOT promoters a Contain binding sites for gene regulatory proteins b Are generally orientation dependent c Are required for basal transcription d May be found upstream or downstream or even inside of the transcribed sequence 8 Which of the following must occur before a mature mRNA can be exported from the a The cap binding complex must be removed b The exon junction complexes must all be removed c The spliceosomes must all be removed d The poly A binding proteins must all be removed e The nuclear export receptor must be removed nucleus 2 eIF2 9 Which of the following describes the effects of phosphorylating eukaryotic initiation factor a Phosphorylation targets eIF2 for ubiquitylation and degradation via the proteasome b Phosphorylation of eIF2 converts it into an inhibitor of its own GEF leading to a c Phosphorylation by the MAP kinase pathway activates eIF2 to act as a d Phosphorylation changes the conformation of eIF2 allowing it to translocate from block in translation transcriptional activator the cytosol to the nucleus 10 Calcium ion concentrations are kept in the cytosol due to the actions of in a High P type pumps plasma membrane and ER b Low V type pumps cytosol c High voltage gated Ca2 ion channels plasma membrane and ER d None of the above 11 Argonaute proteins are involved in the process of a RNA splicing b RNA interference c RNA nuclear export d RNA poly A tail addition Last Name 2 BSCI330 Fall 2012 Exam II KEY Examine the two hydropathy plots in the images below Use these images to answer questions 10 11 12 Which is a plot of a protein that contains amino acid segments that cross the membrane 13 For the protein containing segments that cross the membrane how many transmembrane domains does the hydropathy plot predict there are a Plot A b Plot B a 1 b 5 c 7 d 8 or 9 14 The K ion channel is able to selectively transport K but not Na ions due to the presence of in the selectively loops that are wide enough to accommodate a K but not a Na ion a Four positively charged arginine amino acids b Four carbonyl oxygen atoms c Four polar asparagine amino acids d All of the above 15 Which step in protein translation requires energy from GTP hydrolysis a Linkage of amino acids to tRNA b Binding of the ribosome to the mRNA c Proofreading of the incoming tRNA anticodon codon interaction d Release of the completed protein at translation termination 16 Which of the following was NOT an essential component to the Langmuir Trough experiment carried out by Gorter and Grendell in 1925 a The surface area of the red blood cells they used b The total number of cells used c The volume of lipid monolayer in the trough d The area of the lipid monolayer in the trough Last Name 3 BSCI330 Fall 2012 Exam II KEY Part II Short Answer Questions a 1 In the space provided below please draw a diagram of a lipid bilayer found in a given cell plasma membrane but composed only of lipids In your bilayer identify by name which lipids discussed in lecture would be on the extracellular leaflet and which lipids would be on the intracellular leaflet NOTE For this drawing you do not need to draw the specific chemical structures for your lipids you may simply use the head and tail representation shown in lecture 7 pts Image should be similar to the one below in that it Lipids are each drawn with a head and two tails 1 5pt includes names of all lipids shown 0 25 pts per lipid 1 75 pts total shows the correct placement of specific lipids on the extracellular and intracellular leaflet of the membrane 0 25 pts per lipid 1 75 pts total shows which side is inside the cell and which side is outside the cell 1pt shows or mentions that phosphatidyl serine is negatively charged 1pt Outside inside Other notes as discussed in lecture glycolipids come in a variety of structures so as long as at least one hexagon is used for their glycolipid that is fine Cholesterol does not have to be drawn to perfection but must be shown on both the inner and outer leaflets Take off 0 5 pt if it s not b For any TWO of your lipids explain one reason why each lipid is specifically abundant on that side of the cell membrane 2pts Glycolipids are on the outside because they play a role in cell adhesion and cell cell recognition Phosphatidyl inositol is on the inside because it plays a role in cell signaling Phosphatidyl serine located on inner leaflet contributes to negative charge on inner membrane Last Name 4 BSCI330 Fall 2012 Exam II KEY 2 Unlike DNA RNA can fold into complex 3 D structures Give one example of a 3 D RNA structure that is important in the regulation of gene expression and briefly explain how that structure is important for its function 4pts tRNA structure is important for recognition by aminoacyl tRNA
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