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The following amino acid sequence was derived from the DNA sequence of a gene

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The following amino acid sequence was derived from the DNA sequence of a gene encoding a hypothetical type I integral plasma membrane protein. (The ? merely indicate every 10 amino acids beginning with M1 & ending with V140). Use this information as necessary to answer questions 1-2.;MGIIVLLLLW?VIALILAVAV?EKCPLLYINC?TRLSPQRTNY?SQRPLLFFWM?VILIVLALIF? LVIIVMPKKP? KDSHYRILVT?KHEDQNITEH?KRPDGEECTS?KRIANPTYCP?RKDELQLHDV?KRIANPLWCP? RKDELQLHDV;What localization and/or topogenic sequence(s) does this hypothetical protein contain?;A. Internal signal anchor.;B. N-terminal signal sequence + internal signal anchor.;C. N-terminal signal sequence + stop transfer anchor.;D. N-terminal signal sequence + stop transfer anchor + ER retrieval sequence.;E. Internal signal anchor + ER retrieval sequence.;Question 2 of 5;Which amino acids could undergo Man8 glycosylation in the ER?;A. N29 & N39;B. N86 & N105;C. S34 & S41;D. S73 & S100;E. None of the above. Man8 glycosylation occurs in the cis-golgi;Question 3 of 5;Time for a chimeric protein.;As you'll recall, Hac1 protein (HAC1P) is involved in the unfolded protein response. Using recombinant DNA techniques, you generate a chimeric HAC1P to which you have added the the first 21 amino acids encoded by the LDL receptor gene at its N-terminus, recognition sites for NAGPT, a binding site for AP2, and finally, changed the last 4 amino acids to leu-asn-gly-lys. Where is this chimeric HAC1P going to be directed as its final destination?;A. Chimeric HAC1P will remain in the cytosol.;B. Chimeric HAC1P will be targeted to the nucleus.;C. Chimeric HAC1P will become a resident ER protein.;D. Chimeric HAC1P will be targeted to the lysosome.;E. Chimeric HAC1P will be targeted to the plasma membrane.;Question 4 of 5;Which of the following would you observe for a GFP fusion protein containing an N-terminal signal sequence & whose last 4 amino acids are Asn-Pro-Val-Tyr?;A. It?s a type I integral plasma membrane protein with NANA glycosylation.;B. It?s a protein that is targeted to the lysosome with Man8 glycosylation.;C. It?s a resident ER protein with Man5 glycosylation.;D. It?s endocytosed from the plasma membrane, dissociates in the late endosome and recycled back to the plasma membrane.;E. It?s secreted with NANA glycosylation.;Question 5 of 5;Using recombinant DNA techniques, you generate a chimeric glutathione reductase (GR) that now has the first 21 amino acids encoded by the LDL receptor gene at its N-terminus and the last 4 amino acids also from the LDL receptor at its C-terminus. What are you likely to observe if you expressed this chimeric GR gene in an otherwise normal cell?;A. Chimeric GR protein would undergo Mannose-6P modification in the cis-golgi and accumulate in the lysosome bound to intracellular cholesterol.;B. Chimeric GR protein would be a type I integral membrane protein capable of endocytosing LDL particles.;C. Chimeric GR protein would accumulate in the ER, increase the ratio of GSSG:GSH thereby promoting disulfide bond formation & enhancing protein folding.;D. Chimeric GR protein would accumulate in the ER, increase the ratio of GSH:GSSG thereby inhibiting disulfide bond formation & enhancing protein misfolding.;E. Chimeric GR protein would be secreted with no physiological effects.;Question 1 of 5;You observe that a particular protein is modified by Glucosidase II and UDP-glucose-glycoprotein glucosyl transferase, but not Mannosidase I if otherwise normal mammalian cells are incubated at 40?C. However, this same protein is modified by Glucosidase II, Mannosidase I and N-Acetylglucosamine phosphotransferase if these cells are incubated at 32?C. Identify the protein.;A. The protein is the allele of Mdr1 present in drug-resistant tumor cells.;B. The protein is an allele of BiP in which KDEL has been replaced with REDV.;C. The protein is the M6P receptor.;D. The protein is the?F508 allele of CFTR.;E. The protein is an allele of a lysosomal enzyme with a missense mutation.;Question 2 of 5;The lysosomes in cells from individuals with Tay-Sachs (T-S) disease are deficient in hexosaminidase A (HEXA). However, cells from some individuals with T-S exhibit normal lysosomes containing functional HEXA if they are incubated with a small molecule that resembles N-Acetylgalactosamine. Based on this observation, which of the following is the most likely cause of the HEXA deficiency in these particular T-S individuals?;A. T-S cells lack the M6P receptor.;B. T-S HEXA misfolds in the ER and is ERADicated.;C. T-S HEXA lacks recognition sites for NAGPT.;D. T-S cells lack NAGPT.;E. T-S cells lack NAG glycosylation in the medial-golgi.;Question 3 of 5;What causes the conversion of macrophage to foam cells?;A. Macrophage within blood vessels, differentiate into foam cells in response to inflammation.;B. Macrophage within the intima, accumulate excess HDL particles and become foam cells.;C. Macrophage within the intima import LDL particles, accumulate lipid droplets & differentiate into foam cells.;D. Undifferentiated monocytes within the intima import LDL particles, accumulate lipid droplets & differentiate into macrophage which are also called foam cells.;E. Undifferentiated monocytes within the bloodstream import LDL particles, accumulate lipid droplets & differentiate into macrophage which are also called foam cells.;Question 4 of 5;Why is the majority of cholesterol in the LDL particle esterified to linoleic acid?;A. To increase the fluidity of the LDL particle so it?s less prone to clog an artery.;B. To increase the amount of cholesterol packaged inside the LDL particle.;C. To reduce the concentration of linoleic acid in the bloodstream.;D. To reduce the amount of cholesterol packaged inside in the LDL particle.;E. To reduce fluidity of the LDL particle so it?s more compact.;Question 5 of 5;Which of the following describes the relationship between the level of a cell surface endocytic receptor (e.g., the LDL receptor) and the concentration of its corresponding ligand (e.g., the LDL particle)?;A. Receptor level is proportional to intracellular ligand concentration.;B. Receptor level is proportional to extracellular ligand concentration.;C. Receptor level is inversely proportional to intracellular ligand concentration.;D. Receptor level is inversely proportional to extracellular ligand concentration.;E. There is no relationship between receptor level and its ligand concentration.

 

Paper#15199 | Written in 18-Jul-2015

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