1 Exam 4/Final Biol 213-503 Molecular Cell Biology Fall 2012 Neatly printed name_______________________________________ UIN_______________________________ Signature________________________________ Please note that there are 161 points on this exam but the maximum score you can receive is 150. The space provided for each question should be sufficient for your answers. Make sure that you have 8 pages for this exam. Questions 1-20 are worth 3 points each. Circle your answer. 1. Entry of a protein into the endoplasmic reticulum starts (a) before the protein begins to be synthesized (b) after some of the protein has been synthesized (c) after proteins synthesis is completed and the poly A tail has been added (d) in bacteria (e) using an entrosome 2. Vesicle fusion to the plasma membrane involves (a) v-SNAREs and bindins (b) v-SNAREs and glycosylations (c) v-SNAREs and t-SNAREs (d) valine 23 (e) the Lys-Asp-Glu-Leu (KDEL) plasma membrane localization signal 3. Neutrophils ingest bacteria using (a) phagocytosis (b) pinocytosis (c) exocytosis (d) bactocytosis (e) goblocytosis 4. Lysosomes contain all of the following except (a) polymerases (b) phosphatases (c) sulfatases (c) nucleases (d) phospholipases 5. At the growing end of a microtubule, you would expect to see (a) GTP tubulin (b) GDP tubulin (c) ATP tubulin (d) ADP tubulin (e) unlabeled tubulin 6. Motor proteins that interact with the cytoskeleton inside cells include (a) dynamins, kinesins, and myosins (b) dynamins and myosins (c) dynamins, kinases, and myosins (d) dyneins, kinesins, and myosins (e) none of the above2 7. A very characteristic feature of steroid hormone receptors is that they (a) have just 1 transmembrane domain. (b) act as transcription factors. (c) have 6 transmembrane domains. (d) have 7 transmembrane domains. (e) have 12 transmembrane domains. 8. G proteins can bind (a) just GTP. (b) just GDP. (c) just GMP. (d) both a and b. (e) both a, b, and c. 9. IP3 is a second messenger that (a) converts ATP to cAMP (b) converts ADP to cAMP (c) increases cytosolic Ca++ (d) decreases cytosolic Ca++ (e) activates G proteins 10. MAP kinase cascades are often activated by (a) Ras. (b) G proteins. (c) Diacylglycerol (DAG). (d) IP3. (e) Ca++. 11. The Ras protein is active when (a) it has bound cAMP. (b) it has bound cGMP. (c) it has bound GDP. (d) it has bound GTP. (e) it is released into the cytosol. 12. S phase cyclins regulate (a) G1 (b) G2 (c) mitosis (d) binding of proteins to the origin of replication (e) the phosphorylation states of the M and S cyclins 13. Caspases (a) activate proteases. (b) inactivate proteases. (c) activates proteases and inactivate kinases. (d) inactivate proteases and activate kinases. (e) none of the above.3 14. All of the following are hallmarks of cancer except (a) evasion of growth suppressor signaling. (b) genome instability. (c) activation of apoptosis. (d) angiogenesis. (e) increased glycolysis. 15. Loss of the APC gene always causes (a) increased ploidy (b) altered glycosylation (c) altered Ras activation (d) colon cancer (e) colon polyps 16. The biological activity of a protein is determined by its: (a) peptide bonds. (b) amino acid sequence. (c) ability to form alpha helices. (d) ability to form beta sheets. (e) ratio of alpha helices and beta sheets. 17. Oxidizing glucose via multiple steps, as in cellular respiration, compared with its combustion to CO2 and H2O in a single step provides what advantage to a cell? (a) More CO2 is produced for a given amount of glucose oxidized. (b) Energy can be extracted in usable amounts. (c) More free energy is released for a given amount of glucose oxidized. (d) Less O2 is required for a given amount of glucose oxidized. (e) No energy is lost as heat. 18. A reaction occurs spontaneously only if: (a) ΔG < 0. (b) ΔG > 0. (c) [reactants] > [products]. (d) ΔG = 0. (e) temperature is increased. 19. Phospholipids aggregate to form cell membranes because: (a) they are water fearing. (b) they are amphipathic. (c) they are attached to acids. (d) they are attached to sugars. (e) they are scared. 20. Which statement is false? (a) Feedback inhibition is a negative feedback system for controlling enzyme activity. (b) In feedback inhibition, an enzyme acting early in a reaction pathway is inhibited by a late product of that pathway. (c) Feedback inhibition regulates the flow through biosynthetic pathways. (d) Feedback inhibition is difficult to reverse and requires synthesis of new enzymes. (e) Feedback inhibition helps maintain physiological homeostasis in cells.4 21. If glucose transporters are opened in the plasma membrane of a cell that was previously at rest, how will the membrane potential be affected? (a) The membrane potential is not affected by glucose. (b) It becomes more negative. (c) It becomes more positive. (d) It is permanently reset. (e) It becomes more glucotic. 5 points 22. Why do patients with familial hypercholesterolemia have abnormally high levels of serum cholesterol? 5 points 23. How do proteins get targeted to the mitochondria? 5 points 24. Selectins are glycoproteins that help neutrophils move to the site of an infection. Defective selectin glycosylation is associated with increased frequency of infections in patients. Please explain how proteins get glycosylated. 5 points 25. Immunoglobulins are a key part of the adaptive immune system, and contain disulfide bonds. Please draw a typical disulfide bond, including the two key carbon atoms. 3 points 26. What are the three main types of cytoskeletal proteins inside cells?5 7 points 27. Using diagrams, please explain how a neutrophil in your lungs moves from one place to another inside a tissue (not in the blood). 5 points 28. Tropicamide (Mydriacyl) is a muscarinic acetylcholine receptor antagonist used in eye drops to dilate pupils during a routine eye exam. You are an opthamologist, and a patient asks you to explain the difference between an agonist and an antagonist. Please explain. 5 points 29. You are a developmental biologist studying zebrafish embryogenesis. You are reading a journal article that shows experiments indicating that retinoic acid functions as a paracrine signal that regulates the development of embryos. What is the