BCMB 8020 Exam III Name _____________________________ April 1, 2010 True / False (1/2 point each; 10 points total) 1. Regarding bacteria, ___ both Gram positive and negative microbes utilize a Sec-dependent transport system ___ H. pylori infection involves injection of a virulence factor into the host by a Type I secretion system ___ approximately 33% of the population has suffered an H. pylori infection ___ approximately 50% of stomach cancers are associated with H. pylori infection 2. Based on lecture and your reading of “Protein translocation across the eukaryotic endoplasmic reticulum and bacterial plasma membranes” by Rapoport, the protein conducting channel: ___ is composed of a heterotetrameric complex (i.e. 4 distinct subunits) ___ forms an hourglass-shaped pore with the constriction near the ribosome attachment site ___ is self-sufficient for mediating transport of polypeptides (i.e. extra factors/energy is not needed) ___ interacts with signal sequences that have inserted as a loop (N-terminus toward the cytosol) 3. Regarding lipid biosynthesis, ___ acetyl-CoA is a common precursor to both fatty acid and isoprenoid lipids ___ ATP is used during the synthesis of both fatty acid and isoprenoid lipids ___ NADPH is used during the synthesis of both fatty acid and isoprenoid lipids ___ products with an even number of carbons are generated by the fatty acid biosynthetic pathway 4. Based on your reading of “Lipid Rafts as a Membrane Organizing Principle” by Lingwood et al: ___ cholesterol preferentially associates with the liquid ordered (Lo) phase in purified lipid systems ___ the liquid disordered (Ld) phase has a thicker width than the Lo phase in purified lipid systems ___ the terms Lo and Ld are terms that apply to biological membranes ___ the width of lipid rafts in biological membranes is typically in the micrometer range 5. The phosphorylation event associated with transport by the P-Type Ca2+ pump: ___ occurs on a Ser residue ___ is mediated by GTP ___ induces structural rearrangements of the transporter ___ contributes to formation of a desolvation ring Multiple Choice (2 points each; 26 points total; one correct answer per question) 6. A friend of yours is employed as a pharmaceutical researcher and has just developed a new FDA-approved drug. What is the probability that the target of the drug is a membrane protein? A) 10% B) 25% C) 50% D) 75% 7. Based on the reporters used for the FRAP movies shown in class, which membrane has a more dynamic character? A) endoplasmic reticulum B) Golgi C) plasma membrane D) nuclear membraneBCMB 8020 Exam III Name _____________________________ 2 8. Which of the following locations does not necessarily require a polypeptide-based import signal for transport of newly synthesized small proteins (≤ 5 kDa)? A) endoplasmic reticulum B) nucleus C) periplasmic space of Gram negative bacteria D) peroxisome 9. Together, the membranes of the endoplasmic reticulum and mitochondrial represent approximately what percent of total membrane in a typical eukaryotic cell? A) 25 B) 33 C) 67 D) 90 10. If you want to radiolabel glycerophosphatidylcholine (PC), which of the following would you use? Assume that you have phosphatidic acid, unmodified head groups, and other necessary reagents/enzymes as starting reagents. A) 32P-ATP B) 32P-CTP C) 32P-GTP D) none of the above 11. The ENTH domain binds: A) calcium B) diacylglycerol C) phosphoinositide lipids D) C-termini of certain proteins 12. Based on your research of the topic, which of the following tissue has the highest concentration of docosahexaenoic acid (DHA)? A) blood cells B) brain C) liver D) muscle 13. A key step in hedgehog biosynthesis looks much like which of the following protease mechanisms? A) aspartic acid B) cysteine C) serine D) metallo 14. With respect to the serine protease mechanism, the proton associated with the nucleophilic hydroxyl is transferred to: A) a histidine and eventually returned to the serine B) the C-terminal portion of the product C) the N-terminal portion of the product D) waterBCMB 8020 Exam III Name _____________________________ 3 15. Which of the following types of lipid modified proteins has a free/unmodified carboxyl terminus? A) cholesterol modified B) GPI-linked C) isoprenylated D) S-acylated 16. Which of the following has to be modified by the methionine aminopeptidase? A) PKA B) Ras C) SNAP-25 D) Hedgehog 17. P-type transporters share a common architecture with most of their differences confined to which domain? A) actuator B) hinge C) phosphorylation D) transmembrane 18. Which of the following is not a site from which ABC-type transporters access their substrates? A) cytosolic environment B) extracellular environment C) inner leaflet of plasma membrane D) outer leaflet of plasma membrane Short Answer - These can be answered using keywords, lists, diagrams, and/or 1-2 sentences (1-4 points each; 36 points total) 19. You have radiolabeled versions of each amino acid at your disposal. Which amino acid would you use to radiolabel all sphingolipids? (1 point) 20. Using your knowledge of FRET and the graphic below, provide an identity for each curve (A-D) using combinations of these terms: acceptor, donor, emission, excitement. (4 points) A. _____________________________________ B. _____________________________________ C. _____________________________________ D. _____________________________________ 21. What are the distinct experimental approaches described in class as being used to establish juxtaposition of extracellular GPI proteins and intracellular Src family kinases across from each other at the plasma membrane? (2 points)BCMB 8020 Exam III Name _____________________________ 4 22. Using the stick figure method, draw the chemical structure of a naturally occurring 16:2(∆6,11) fatty acid. (4 points) 23. What is a major molecular/protein target of cocaine AND how does it affect the function of its target? Specific mechanistic information on the interaction is not required for the answer. (2 points) 24. A ‘seal’ holds the ribosome and protein translocation channel together. What are the key features of the mRNA needed for setting up the quenching experiment described in class/lecture that was used to assess the tightness of the seal? (3 points) 25. Sphingomyelin synthesis directly depends on which glycerophospholipid?