Part I Multiple Choice 1 5 pts each 30pts 1 The face of the Golgi is closest to the ER a Cis b Trans 2 A newly synthesized protein destined to reach the plasma membrane has N terminal ER signal sequence and no START or STOP TRANSFER sequences Which of the following must be true about this protein circle all that apply It will be a membrane receptor it will be soluble and secreted out of the cell once it reaches the plasma membrane it will be a single pass transmembrane protein a b c d It will be found in the lumen of a transport vesicle at some point 3 A cell with a dysfunctional TOM complex would most likely accumulate in the 4 The actions of Rho GTP would likely form what structures in a cell 5 Which of the following is a possible destination of a receptor after it has undergone a Misfolded proteins ER b Mitochondrial proteins cytosol c ER resident proteins cytosol d Misfolded proteins nucleus a Lamellopodia b Stress fibers c Filopodia d Membrane ruffles endocytosis a Recycling to the cell surface b Degradation in lysosomes c Transcytosis d All of the above e None of the above you predict to be true about it 6 You have identified a lipase that is optimally active at pH 5 Which of the following would It is a Golgi resident protein a b It is synthesized in the cytosol and then translocated into the mitochondria c d None of the above It contains a KDEL sequence 1 7 Vesicles that leave the trans Golgi destined for early endosomes would have which kind of 8 Which of the following is an important component of muscle contraction 9 Circle all of the organelles in the list below that are topologically equivalent to the 10 Which of the following ligands would you expect to bind to a member of the nuclear 11 Which of the following second messengers will lead to activation of protein kinase A PKA 12 Which of the following protein modification events does NOT occur in the Golgi a Addition of carbohydrate to serine residues b Pruning of N linked carbohydrates c Addition of mannose 6 phosphate tags d Trimming by proteolytic enzymes e None of the above i e all can occur in the Golgi 13 ATP is involved in mediating which of the following cytoskeletal processes choose all that apply a Microtubule polymerization b Dynamic instability c Treadmilling d Muscle contraction coat protein a COPI b COPII c clathrin d retromer a Myosin b Actin microfilaments c Troponin d All of the above extracellular space a ER b Golgi c Nucleus d Mitochondria e Lysosomes receptor subfamily a Acetylcholine b LDL c Transferrin d Cortisol IP3 a b cyclic AMP c diacylglycerol 2 17 describes the process in which the ends of undergo rapid 14 A toxin that inhibits GTP binding to proteins is also found to accumulate transport vesicles in the cytosol What specific GTP binding protein GTPase is the toxin likely to be inhibiting a Rab b Ran c Rho d Ras 15 Cells use pinocytosis to a Engulf large particles b Degrade damaged organelles c Secrete signaling molecules in a regulated fashion d Take up fluid from the extracellular environment 16 According to the Cell Biology of Taste article the umami taste is elicited by what types of substances a Sugars b Organic toxins c Amino acids d Na ions shrinkage a Rescue microtubules b Treadmilling actin microfilaments c Catastrophe microtubules d None of the above response a Rapid b Slow a Retained in the ER b In lysosomes c Getting secreted out of the cell d None of the above 18 Extracellular signals that result in changes to the expression of a gene would likely cause a 19 A protein bearing a mannose 6 phoshpate M6P tag will ultimately end up 20 Which of the following accurately describes what is happening at the plus end of a microtubule that is undergoing rapid growth a The rate of GTP hydrolysis is exceeding the rate of subunit polymerization b There are more GDP bound subunits than GTP bound subunits c d None of the above the rate of subunit polymerization is exceeding the rate of GTP hydrolysis 3 Part II Matching 2 pts each 24pts Please match each of the descriptions in column A with the corresponding terms in column B Note A given term may be used once more than once or not at all Each description has only ONE correct answer 23 J involved in protein folding in D KDEL receptor Column A Descriptions 21 K cytosolic facilitates release of nuclear import receptors from Ran 22 C during translation of mRNA molecules will be found either in cytosol or on ER membranes the ER 24 F Initial translocator for all mitochondrial membrane proteins 25 A Required for docking tethering of vesicles onto target membranes 26 O Required for pinching off of clathrin coated vesicles 27 L translocator for inner mitochondrial membrane proteins 28 M important for lysosomal acidification 29 I confined to nucleus required for Ran mediated nuclear export 30 C Recognizes ER signal sequences 31 D Involved in retrograde transport from Golgi to ER 32 H Required for fusion of vesicles with target membranes 4 Column B Terms B M6P receptor A Rab C SRP E Secretory vesicles F TOM complex G Sar1 H SNAREs I Ran GEF J Calnexin K Ran GAP L TIM23 complex M V type ATPase N Cdc42 O Dynamin Part III Short Answer Questions 28pts 4pts each 33 Describe ONE type of experiment presented in lecture that can be used to determine the organelle localization of a given protein 1 Fluorescence microscopy can be used to determine where in the cell the protein localizes Mutations can be generated within the protein to determine the effects on its localization 2 Density gradient centrifugation can be used to fractionate cells expressing the protein into distinct organelle fractions to determine whether the protein co fractionates with a specific organelle 3 Molecular weight changes of the protein due to cleavage by organelle proteases can be examined by SDS PAGE 4 A Protease Protection Assay can be used to determine whether a given protein is localized within an organelle compartment In this method organelle fractions are treated with or without an outside protease in the presence or absence of detergent Fusion proteins localized within an organelle compartment should theoretically be protected from cleavage by an outside protease This protection is detergent sensitive since detergents can break up membranes The resulting size differences between cleaved and uncleaved versions of the protein can be detected as mobility differences on protein gels 34 The maturation of endosomes includes their gradual acidification List TWO ways that the reduction
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