BIO-327-Cell-Biology-FA-2021-exam4_A-KEY

Bio 327 Fall 2021 Exam 4 Version A Name ___________________ All 42 questions are worth 1.25 points SU ID ____________________ Circle/indicate the one correct answer on both your exam booklet and scantron answer sheet. 1. True/False: Channels as opposed to carrier proteins in ion transport are the same as gap junctions in that they are non-selective and when open allow many, many ions to pass at once? a. True b. False 2. True/False: Plant cells orient their cellulose synthesis relative to stomata found in the cell cortex a. True b. False 3. A type of stem cell can give rise to several different types of intestinal cells, but no other types of cells. Therefore, we label this type of stem cell: a. Induced b. Totipotent c. Unipotent d. Multipotent e. Pluripotent 4. Which of the following represents the most well-proven use of human stem cells to cure or treat a human disease? a. Human embryonic stem cells to treat Parkinson's Disease b. Neural stem cells to repair spinal cord injuries c. Bone marrow transplants to treat leukemia d. Bone marrow cells to treat heart attack patients e. Both B and D are well-proven uses. 5. Tumor suppressors are defined as genes whose loss of function leads to cancer development. Which of the following is/are well known tumor suppressors? a. RNA polymerase b. Ras c. Rb d. p53 e. C and D 6. True/False: CAR-T cells are promising as cancer therapeutics because once introduced to a patient these cells will typically target essentially all types of tumors and cancer cells arising in the body a. True b. False

7. NADPH and Acetyl CoA are examples of a class of molecules called _________ that cells use to create a favorable (that is a net ________) change in free energy, delta-G, for many otherwise energetically unfavorable reactions that occur in the cell. a. activated carriers; negative b. reducers; negative c. polymerases; positive d. ions; positive e. oxidizers; positive 8. The function of a signal sequence found in a secreted eukaryotic protein is to be recognized by the ___________ which pauses translation by the ribosome until it is docked on the __________ membrane where the nascent polypeptide can be translocated into the lumen of that compartment via a translocation channel. a. v-SNARE; nuclear b. signal recognition particle (SRP); plasma c. COP coat protein; mitochondrial d. v-SNARE; t-SNARE e. signal recognition particle (SRP); endoplasmic reticulum (ER) 9. The phosphorylation of a protein is typically associated with a change in activity, the assembly of a protein complex, or the triggering of a downstream signaling cascade. The addition of ubiquitin, a small polypeptide, is another type of covalent modification that can affect the protein function. Ubiquitylation often results in ______________. a. protein degradation b. membrane association c. protein secretion d. protein refolding via chaperones e. nuclear translocation 10. RTKs are a class of cell surface receptors. They are activated by: a. Glycosylation b. GTP/GDP nucleotide binding and hydrolysis c. proteolysis d. dimerization and subsequent phosphorylation on tyrosine residues e. None of the above 11. Proteins such as Ras, Ran and Rab, as well as G α are all regulated by a. glycosylation b. GTP/GDP nucleotide binding and hydrolysis c. proteolysis d. phosphorylation on Ser, Thr, or Try residues e. None of the above

17. Protease activities are known to be used to ensure the correct assembly/disassembly and functioning of the following proteins for each of the following processes EXCEPT: a. Correct docking of transport vesicles to their appropriate target membrane b. Correct assembly and processing of proinsulin into mature/functional insulin c. Correct processing and assembly of procollagen into mature/functional collagen d. Caspases involved in apoptosis e. Cyclin-mediated progression of the cell cycle 18. Which of the following is false? a. all eukaryotic cells contain at least one nucleus b. In humans, some cells contain more than one nucleus c. The Central Dogma of Molecular Biology DNA >RNA>Proteins is common to all living organisms d. All cells require energy e. All of these answers are true 19. Why are glycolipids and glycosylated regions of membrane resident proteins found on the extracellular, but not the cytoplasmic, surface of the plasma membrane? a. Flippases transport them from the cytosolic face. b. The oligosaccharides on glycolipids are cleaved off by enzymes found only in the cytosol. c. They can flip spontaneously, after incorporation, due to the hydrophilic sugar head groups. d. The enzymes that add the sugar groups are confined to the inside of the endoplasmic reticulum and the Golgi apparatus. e. The enzymes that produce them are present only on the extracellular surface of the plasma membrane. 20. Phospholipids can form bilayer membranes because they are ________. The fluidity and permeability of membranes are most directly related to __________ and __________, respectively. a. Hydrophobic : phospholipid tail unsaturation : membrane protein/lipid content ratios. b. Amphipathic : phospholipid tail unsaturation : cholesterol content c. Amphipathic : phospholipid tail unsaturation : membrane protein/lipid content ratios. d. Hydrophilic : phospholipid tail length : cholesterol content e. Hydrophobic : phospholipid tail length: membrane protein/lipid content ratios. 21. What proteins help provide the energy to deform the underlying membrane during the process of vesicle formation? a. t-SNARE b. coat proteins c. v-SNARE d. flippase e. chaperone

22. Which statement of the following about enzymes is FALSE? a. Enzymes can work by positioning two substrates close to one another to promote their reaction. b. An enzyme can direct a molecule along a particular reaction pathway by selectively lowering the energy necessary to make the reaction occur. c. Enzymes can work by changing the equilibrium constant of reactants that form a product to make the equilibrium constant more favorable. d. Most enzymes are proteins although some are RNAs. e. Their ability to associate with their substrate can be described by the Michaelis Menten value of Km. 23. If DNA is damaged or incompletely replicated, what key protein senses this and when activated causes expression of p21 protein, thereby pausing the cell cycle so that the DNA can be repaired before continuing on in the cell cycle? a. p53 b. S-Cdk c. ORC d. Cdc6 e. Cdc25 24. What must happen for a Cdk to be active? a. It must be switched on by proteolysis b. It must bind to its cyclin partner. c. It must dissociate from its bound cyclin. d. It must translocate from the cytoplasm to the nucleus. e. It must increase in concentration at a specific time in the cycle. 25. Soon after nerve growth factor (NGF) was discovered, investigators injected newborn mice with antibodies that inactivated it. Compared to control mice, those that received the antibody showed massive amounts of nerve cell death. After a week of daily antibody injections, up to 99% of the neurons in certain parts of the nervous system of these mice were gone. What do these results suggest? a. NGF signaling is sufficient for survival of developing neurons. b. NGF cannot protect developing neurons from death by apoptosis. c. NGF is a mitogen that promotes the proliferation of developing neurons. d. NGF is a survival factor for developing neurons. e. NGF triggers apoptosis in developing neurons. 26. In cells undergoing apoptosis, nuclear lamins are cleaved by which of the following? a. initiator caspases b. nucleases c. executioner caspases d. procaspases e. b and e are correct

32. The expression levels of different ___________ fluctuate throughout the cell cycle. a. phosphates b. cyclins and Cdks c. cyclins d. Cdks e. a and b are correct 33. Which of the following animal tissues is characterized by a plentiful extracellular matrix? a. nervous b. connective c. epithelial d. muscular e. none of the above 34. Hemidesmosomes serve what function? a. connect adjacent cells to one another in a tissue to help maintain mechanical integrity b. connect cells to basal lamina to help a tissue maintain mechanical integrity c. connect cells to one another to allow movement of small molecules between cells in a tissue d. connect cells to one another in an epithelium to create a tight seal between the cells e. all of the above 35. Which of the following are the plant equivalent of a gap junction? a. desmosomes b. plasmodesmata c. tight junctions d. adherens junctions e. c and d are correct 36. Stem cells hold great promise both for studying cell fate determination and organ development and for clinical use, such as blood stem cell transplants to treat patients whose own immune systems have been severely impaired. Clinicians also hope that stem cells can be coaxed into specific cell types to treat diseases in which that cell type is damaged, such as replacing neurons in Parkinson’s disease. In 2008, researchers assessed the ability of neurons derived from reprogrammed fibroblasts to ameliorate the symptoms of Parkinson s disease in a rat model. Based on your knowledge of stem cells and cell differentiation, what intermediate step was necessary to convert fibroblasts into neurons? a. converting fibroblasts into embryonic stem cells via introduction of transcription factors b. converting fibroblasts into induced pluripotent stem cells c. converting fibroblasts into organoids in culture d. converting fibroblasts into embryonic stem cells via introduction of tumor suppressor genes e. putting the cells inside a plant’s stem for three days

37. In most cases, about how many mutations are required for a normal cell to turn into a cancer cell? a. generally, only one b. more than three c. thousands in different genes d. Cancers are not caused by mutations. e. please enjoy your break and do not pick this choice 38. Which type of mutation would not typically convert a proto-oncogene into an oncogene? a. chromosomal deletion of the region containing the proto-oncogene b. chromosomal rearrangement that leads to overproduction of the normal proto-oncogene protein c. chromosomal rearrangement that leads to the production of a hyperactive protein d. a mutation in the coding sequence that leads to the production of a hyperactive protein e. gene amplification 39. True/False: For an Action Potential to occur, the incoming electrical signal must exceed a threshold potential wherein Na + channels open abruptly causing Vm to depolarize towards E Na , after which the Na + channels are inactivated, and special K + channels open. a. True b. False 40. Na+ is kept at a low concentration within cells by the activity of what? a. active transport by Na+ / K+ pumps b. passive diffusion through the plasma membrane c. active transport through Na+ channels d. passive diffusion through Na+ channels e. b and c are correct 41. Bonus –The apical villi seen on polarized epithelial cells and the cristae made up of invaginations of the mitochondrial membrane are both examples of which principle discussed in this course? a. combinatorial control d. the Central Dogma of Molecular Biology b. information movement and transfer e. parallel analyses c. form follows function 42. Bonus – When proteins are composed of more than one polypeptide chain such as the structure of hemoglobin containing two alpha subunits and two beta subunits, or the heterotrimeric G protein associated with GPCR signaling, this level of protein structure refers to the: a. primary structure d. quaternary structure b. secondary structure e. Lego structure c. tertiary structure