Cell Biology Final at UCD Grade for Jeffrey Bornstine: Unit 10 Exam Numeric grade: 90/100 Letter grade: A Comments: (none) Close Window Autograde Summary Date Taken: 7/31/2007 3:32:43 PM Time Spent: 2:58:46 (3:00 allowed) Points Received: 90 / 100 (90%) These are the automatically computed results of your exam. Grades for essay questions, and comments from your instructor, are in the Details section below. Question Type: # Questions: # Correct: Multiple choice 50 45 JavaScript is required for your course. Please ensure JavaScript is enabled in your browser preferences. Grade Details 1. Question: The binding of alanine to tRNAala is mediated by the enzyme ______ . Your Answer: aminoacyl-tRNA synthase amino-tRNA synthetase aminoacyl-tRNA synthetase CORRECT amino-tRNA syntase Points Received: 2 of 2 Comments: 2. Question: The enzymatic activity of _____ binds the incoming amino acid to the newly forming peptide during the elongation step of translation. This activity was once thought to be a _________-associated activity, but is now believed to be _______-associated activity. Your Answer: transferase, ribosomal, protein heteramino-transferase, protein, ribosomal peptidyl-aminase, protein, ribosomal peptidyl-transferase, protein, ribosomal CORRECT peptidyl-transferase, ribosomal, protein Points Received: 2 of 2 Comments: 3. Question: The process by which the ER uptakes an incipient (new) polypeptide concurrent with the translation of the peptide is called ______. Your Answer: co-import translation co-translational import CORRECT co-transcriptional import co-transport Points Received: 2 of 2 Comments: 4. Question: Polypeptides destined to be secreted, or associated with endosomes or the plasma membrane, have a special consensus sequence of 15-20 amino acid residues at the N-terminus called the ______. Your Answer: signal recognition sequence INCORRECT signal peptide sequence peptide recognition sequence recognition sequence sometimes called a or b. CORRECT ANSWER Points Received: 0 of 2 Comments: 5. Question: Use the tRNA molecule seen below to answer questions 5 and 6. Amino acids bind to the _____ end of the tRNA and are linked to the tRNA via a _________ bond. Your Answer: 5, thio-ester 5, thio-ether 5, phosphodiester 3, thio-ether 3, ester CORRECT 3, ether Points Received: 2 of 2 Comments: 6. Question: The numbers 1, 2 and 3, are the nucleotides of the anticodon for the mRNA codon 5 AUG 3. Thus, in the order of 1, 2 and 3 the sequence of this anticodon is ______. Your Answer: UTG ATG GUA CAU CORRECT Points Received: 2 of 2 Comments: 7. Question: The nuclear scaffolding is made up of which cystoskeletal element? Your Answer: microtubules microfilaments intermediate filaments CORRECT Points Received: 2 of 2 Comments: 8. Question: The _________ particle __________ halts the translation of the mRNA to a polypeptide before docking to the ER. Your Answer: signal recognition , permanently signal recognition protein receptor, permanently signal recognition, temporarily CORRECT signal recognition protein receptor, temporarily Points Received: 2 of 2 Comments: 9. Question: For membrane-associated proteins, the consensus sequence _____ is found on the inchoate (new) polypeptide and causes ___________ to halt. Your Answer: pribnow, replication signal peptidase, transcription stop-transfer peptide, transcription stop-transfer sequence, translation stop-transfer sequence, translocation CORRECT Points Received: 2 of 2 Comments: 10. Question: Methyl-7 Guanosine (m7G) is found at the _____ end of a processed eukaryotic organism’s mRNA. Your Answer: 5 CORRECT 3 C-terminal N-terminal Points Received: 2 of 2 Comments: 11. Question: Movement of flagella and cilia is based on which cytoskeletal element? Your Answer: microtubules CORRECT microfilaments intermediate filaments Points Received: 2 of 2 Comments: 12. Question: The KM for binding GTP by / tubulin is greater/less than/the same (pick one) as the KM for binding GDP? Your Answer: greater less than CORRECT the same Points Received: 2 of 2 Comments: 13. Question: During the plateau phase of microtubule polymerization the concentration of _________ is rate limiting. Your Answer: GTP GDP ATP free tubulin CORRECT Points Received: 2 of 2 Comments: 14. Question: The hydrolysis of GTP to GDP on incorporated / tubulin can promote the ________ of microtubules. Your Answer: disassembly CORRECT assembly movement polymerization Points Received: 2 of 2 Comments: 15. Question: Enhancers and promoters are _____. In contrast, the heterodimer “TFIIA and TFIIB” are examples of ________ . Your Answer: trans-acting elements, cis-acting factors cis-acting elements, trans-activating factors CORRECT cis-activating factors, trans-acting elements trans-activating factors, cis-acting elements Points Received: 2 of 2 Comments: 16. Question: A peptide hormone binds ________ to its receptor. Your Answer: permanently covalently temporarily CORRECT ironically Points Received: 2 of 2 Comments: 17. Question: Taxol and colchicine affect microtubule structures. The first is a(n) ______ inhibitor and the second is a(n) _______ inhibitor. Both affect cell division. Taxol ________ cell division by _________ microtubules, whereas colchicine ________ cell division by promoting microtubule __________. Your Answer: irreversible, reversible, arrests, destabilizing, disrupts, disassembly reversible, irreversible, disrupts, destabilizing, arrests, treadmilling irreversible, reversible, disrupts, stabilizing, arrests, destabilizing reversibly, irreversibly, arrests, stabilizing, disrupts, disassembly CORRECT Points Received: 2 of 2 Comments: 18. Question: Microtubule Associated Proteins (MAPS) are associated with the positive/negative (pick one) end of microtubules. Your Answer: positive CORRECT negative Points Received: 2 of 2 Comments: 19. Question: The primary function of the second messenger is to ____ the external signal of the hormone. Your Answer: diminish amplify CORRECT translate transduce Points Received: 2 of 2 Comments: 20. Question: The ____-subunit of most heterotrimeric G-proteins binds the guanine nucleotides and acts as a _______. Your Answer: beta, ATPase gamma, GTPase alpha, ATPase gamma, ATPase alpha, GTPase CORRECT Points Received: 2 of 2 Comments: 21. Question: cAMP molecules bind to the _______ subunits of ______. Your Answer: catalytic, PKC regulatory, PKA CORRECT regulatory, PKC catalytic, PKA Points Received: 2 of 2 Comments: 22. Question: The second messengers IP3 and DAG are products of PIP2 hydrolysis. The enzyme that promotes the production of these two molecules is called _____________. Your Answer: phosphase C lipase C phospholipase D phospholipase C CORRECT phosphatase C Points Received: 2 of 2 Comments: 23. Question: The molecule below represents PIP2. In the spaces to the right of the figure, are letters that designate parts of PIP2 that become IP3 and DAG. >Letters “A” and “B” represent those part of the parent molecule that will become _____ and ______ , respectively upon cleavage of PIP2. Your Answer: IP3, DAG DAG, IP3 CORRECT Points Received: 2 of 2 Comments: 24. Question: DAG activates ____ . In turn this kinase _____ its own substrates. Your Answer: PKA, phosphatates PKA, phosphorylates PKC, phosphatates PKC, phosphorylates CORRECT Points Received: 2 of 2 Comments: 25. Question: Motor proteins such as kinesin and dynein move along the cytoskeleton using the energy generated from the hydrolysis of this phosphorylated nucleotide. Your Answer: GDP GTP ATP CORRECT ADP Points Received: 2 of 2 Comments: 26. Question: After a steroid hormone binds to its receptor, the steroid-receptor complex translocates to the __________ where it binds to a __________. Thus, the steroid-receptor complex acts as a ________. Your Answer: cytoplasm, protein kinase, cis-acting element nucleus, protein kinase, trans-activating factor INCORRECT cytoplasm, DNA sequence, cis-acting element nucleus, DNA sequence, trans-activating factor CORRECT ANSWER Points Received: 0 of 2 Comments: 27. Question: The tau protein is involved in promoting the neurofibrillary tangles of Alzheimers disease. This is due to the ________ of tau proteins. Your Answer: dephosphorylation hyperphosphorylation CORRECT hypophosphorylation normal phosphorylation Points Received: 2 of 2 Comments: 28. Question: Cytochalasin is a drug used by cell biologist to inhibit the addition of ______ during polymerization of this cytoskeletal structure. Your Answer: F-actin tubulin protofilaments G-actin CORRECT Points Received: 2 of 2 Comments: 29. Question: Kinesin and dynein are special MAPS: they are “motor protein” MAPS. Vesicles moving from the ER to the Golgi would be transported by _______, whereas vesicles moving from the Golgi to the plasma membrane would be transported by _______. Additionally, autograde movement in neurons would be mediated by ________, whereas retrograde would be mediated by _________. Your Answer: dynein, kinesin, kinesin, dynein CORRECT dynein, kinesin, dynein, kinesin kinesin, dynein, kinesin, dynein kinesin, dynein, dynein, kinesin Points Received: 2 of 2 Comments: 30. Question: The motor proteins associated with the kinetochore, polar and astral microtubules are all located at the ______ end of their respective microtubules. However, the motor proteins of the kinetochore, polar and astral microtubules move towards the ___, ___, and ___ end of their respective microtubule. Your Answer: positive, positive, negative, positive positive, negative, positive, negative CORRECT negative, positive, negative, positive negative, negative, positive, negative Points Received: 2 of 2 Comments: 31. Question: The drosophila embryo goes through a series of mitotic divisions before cytokinesis occurs. This demonstrates one of the following. Your Answer: cytokinesis is inextricably associated with mitosis mitosis is always followed by cytokinesis cytokinesis is never associated with mitosis cytokinesis is not inextricably associated with mitosis CORRECT Points Received: 2 of 2 Comments: 32. Question: The number ____ and ____ sign are assigned to the first nucleotide of a transcriptional unit. Your Answer: 0, positive 1, negative 1, positive CORRECT 0, no sign Points Received: 2 of 2 Comments: 33. Question: Protein kinases are ubiquitous throughout all eukaryotic cells. The function of a protein kinase is to __________ its substrate using ____ as a source of phosphate molecules. Your Answer: de-phosphorylate, ATP de-phosphorylate, inorganic phosphate phosphorylate, inorganic phosphate phosphorylate, ATP CORRECT Points Received: 2 of 2 Comments: 34. Question: Rb is a “nuclear phosphoprotein”. When phosphorylated it dissociates from the E2F protein and transcription begins. This probably means that the Rb protein _____ the activity of E2F when not phosphorylated, and is itself regulated by the activity of a _________. Your Answer: enhances, phosphatase inhibits, kinase CORRECT enhances, kinase inhibits, nuclease Points Received: 2 of 2 Comments: 35. Question: p53 is important in the regulation of the cell cycle. When DNA is damaged and cannot be repaired, p53 is activated to begin the process of “apoptosis”: programmed cell death. If this molecule is necessary for all cells to maintain vigilance against uncontrolled cell division, then the p53 gene is considered to be a __________ gene. Your Answer: important INCORRECT consensus regular conserved CORRECT ANSWER Points Received: 0 of 2 Comments: 36. Question: The RNA of tumor viruses is converted to DNA by the enzyme_______. Your Answer: retrovirase reverse transcribase retro-transciptase reverse transcriptase CORRECT Points Received: 2 of 2 Comments: 37. Question: Tumor viruses incorporate their genetic material into the genome of the host. At this stage the ________ is hidden within the host’s DNA. Your Answer: protovirus primary virus provirus CORRECT proviron Points Received: 2 of 2 Comments: 38. Question: p53 is a “nuclear protein”. When the cell is damaged there is an upregulation of p53 concentration due to a decrease in its _______. Increased amounts of p53 causes the transcription of p21, a CDK inhibitor. This probably means that p53 acts as a __________. Your Answer: activity, ATPase degradation, transcription factor CORRECT half-life, kinase inhibitor, nuclease Points Received: 2 of 2 Comments: 39. Question: In the mammalian cell system, steroid receptors not bound to their ligand are commonly found ________. Your Answer: in the plasma membrane in clathrin coated vesicles in the cytosol or in the nucleus CORRECT on the nuclear membrane Points Received: 2 of 2 Comments: 40. Question: The microtubule organizing center (MTOC) is the point at which nucleation of microtubules begins. Thus, the MTOC is the positive/negative (choose one) of the newly forming microtubule end, and without which the _________ would not form. Your Answer: negative, Golgi CORRECT positive, Golgi negative, ER positive, ER Points Received: 2 of 2 Comments: 41. Question: Microtubules/microfilaments/intermediate filaments (choose one) are important in increasing the surface area of intestinal microvilli. Your Answer: microtubules microfilaments CORRECT intermediate filaments Points Received: 2 of 2 Comments: 42. Question: Guanine nucleotide binding protein receptors (GBPR) are associated with heterotrimeric G-proteins. When the GBPR is activated by its ligand, the receptor activates its associated G-protein. Subsequently, GTP displaces bound GDP on the _____ subunit of the G-protein. At this moment, the affinity for binding GTP by this subuint is greater/less than/the same as (pick one) the affinity for binding GDP? Your Answer: , less than , less than , the same , greater than CORRECT Points Received: 2 of 2 Comments: 43. Question: The p53 “nuclear phosphoprotein” is a “tumor-suppressor” molecule, and is activated when phosphorylated. When active, it blocks uncontrolled proliferation of a cell by stimulating the expression of a CDK inhibitor that blocks the activities of cell cycle-associated proteins. This suggests that p53 acts as a __________, and is regulated by the activity of a _________. Your Answer: enhancer, ATP transcription factor, kinase CORRECT enhancer, translocase transcription factor, nuclease Points Received: 2 of 2 Comments: 44. Question: Protein kinases are ubiquitous throughout eukaryotic cells. The function of a protein kinase is to __________ its substrate using ____ as a source of phosphate molecules. Your Answer: de-phosphorylate, ATP de-phosphorylate, inorganic phosphate phosphorylate, inorganic phosphate phosphorylate, ATP CORRECT Points Received: 2 of 2 Comments: 45. Question: Poly-adenylation is found on the ______ of the processed mRNA. It is the cells way of ________ the half life of the message. Your Answer: 5, decreasing 5, increasing 3, increasing CORRECT 3, decreasing Points Received: 2 of 2 Comments: 46. Question: The transformation (making cells cancerous) of cells by the oncogenic form of p21Ras is sometimes a result of a nucleotide base-pair substitution in codon #12. The proto-oncogene codon GGC codes for Gly, whereas the oncogene codon GTC codes for Val. This base-pair substitution in codon #12 codes for the ______ amino acid residue of p21Ras. Your Answer: 4th INCORRECT 3rd 36th 12th CORRECT ANSWER Instructor Explanation: . Points Received: 0 of 2 Comments: 47. Question: The production of cAMP is directly regulated by two enzymes, _______ and _______. The former is a ____________ protein, whereas the latter is a __________ protein. Your Answer: Phosphodiesterase (PDE), Adenylyl cyclase (AC), cytosolic, peripheral CORRECT PDE, AC, peripheral, cytosolic Adeylyl kinase (AK), Phosphorylase A (PLA), peripheral, cytosolic Adenyl Cyclase (AC), phsophodiesterase (PDE), integral, peripheral Points Received: 2 of 2 Comments: 48. Question: When epidermal growth factor (EGF) binds to its receptor it changes the conformation of the epidermal growth factor receptor (EGFR) so that it can interact with another EGFR. In order for the EGF signal to be transduced into the cell, two EGFRs must interact with one another for actual activation. Thus, two EGFRs act as a functional _________________________, or in other words, a multimeric polypeptide. Your Answer: tetramer heterodimer homodimer CORRECT homotrimer Points Received: 2 of 2 Comments: 49. Question: When calcium diffuses into the cytosol, it binds to _________. This complex is involved in the production of nitric oxide (NO) by activating the enzyme _____________. Similar to cAMP, the second messenger cGMP is produced by the enzyme _____________. Eventually, striated and smooth muscle tissue ___________. Your Answer: calipain, calmodulin (CaM), guanylyl cyclase (GC), dilate calmodulin (CaM), nitric oxide synthase (NOS), guanylyl cyclase (GC), dilate CORRECT calmodulin (CaM), nitric oxide synthase (NOS), guanylyl cyclase (GC), constricted PKC, nitric oxide synthase (NOS), adenylyl cyclase (AC), dilate Points Received: 2 of 2 Comments: 50. Question: In contrast to RTK’s, MAP kinase (MAPK) is a serine kinase. One of its substrates is the enzyme farnesyltransferase (FTase) (Fig 1). FTase is phosporylated on ___________________ residues 60 and 62 and subsequently activated. When cells are insulin resistant, the metabolic pathway is blocked and the mitogenic pathway is potentiated (Fig 2). When this occurs the activity of MAP kinase is significantly increased and FTase is phosphorylated more quickly. Activation of FTase increases the amount of membrane-associated Ras, whereby more Ras can be activated by binding to GTP (i.e., GTP-loading). When more GTP-bound Ras is active, more insulin signal is propogated via the MAP kinase pathway. Thus, more MAP kinase enzymes become active. This type of mechanism in which the signal continues to upregulate itself is an example of __________________ regulation. FIGURE 1 FIGURE 2 Your Answer: serine, negative threonine, negative tyrosine, positive INCORRECT serine, positive CORRECT ANSWER Points Received: 0 of 2 Comments:
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