Download PCB3109 Exam 1 Questions And Answers and more Exams Cancer Cytogenetics in PDF only on Docsity!
The expression of which of the following contributes to the development of cancer? A. tumor suppressor genes. B. proto-oncogenes C. apoptosis genes D. oncogenes - correct answer ✅D. oncogenes; Explanation: Tumor suppressor genes SUPPRESS tumor formation, proto-oncogenes only contribute once they mutate into oncogenes, and apoptosis genes program cell death. How is cancer treated? A. drugs (chemotherapy) B. radiation C. surgery D. all of the above - correct answer ✅D. all of the above A new compound developed in the lab was tested in the Ames test. When the Ames test was performed, the results were many more bacterial colonies following exposure to the new compound as
compared to a known safe control compound. This result means the new compound: A. is safer than the control B. is radioactive C. is a mutagen and also may be a carcinogen D. would be a great candidate to use for chemotherapy - correct answer ✅C. is a mutagen and also may be a carcinogen; Explanation: The Ames test utilizes bacteria to determine whether a particular chemical can cause mutations in the DNA of the test organism. If there are many more colonies after exposure to the compound compared to the control, it means the compound caused mutations and is a mutagen. It does not determine radioactivity, and it is definitely not safer than the control or a feasible option for chemotherapy due to being a mutagen. Each of the following is true with regard to cancer cells except: A. growth does not require growth factors B. the cell cycle arrest may be disrupted C. growth may proceed despite high levels of DNA damage D. the apoptosis pathway may be blocked E. none of the above - correct answer ✅E. none of the above; Explanation: growth does not require growth factors, cell cycle arrest is disrupted because of
D. cancer cells induce new blood vessels to form whereas normal cells do not E. cancer cells generally have a higher mutation rate as compared to normal cells - correct answer ✅A, B, and E; Explanation: B and C are incorrect because normal cells can move around the body and perform angiogenesis. Which amino acid is hydrophobic? A. Serine B. Leucine C. Asparagine D. Glutamate (Glutamic acid) - correct answer ✅B. Leucine A peptide bond A. is a covalent bond between the NH group of one polypeptide and the CO group of another polypeptide. B. is a covalent bond between the functional R groups of adjacent amino acids. C. is a covalent bond between the carboxyl carbon of one amino acid and the amino nitrogen of a second amino acid.
D. is a non-covalent bond that dictates the tertiary structure of a protein. - correct answer ✅C. is a covalent bond between the carboxyl carbon of one amino acid and the amino nitrogen of a second amino acid. In the alpha-helical secondary structure, the amino acid side chains: A. are buried in the interior of the helix B. provide the hydrogen bonds that form the helix C. are typically polar D. extend outward from the helix spiral E. are located in an alternating arrangement between the inside and the outside of the helix. - correct answer ✅D. extend outward from the helix spiral You are researching a cytoplasmic protein that is upregulated in cancer cells. The native form of the protein appears to be globular protein; however, when a sample of the purified protein is treated with a chemical that reduces disulfide bonds, the activity of the protein decreases dramatically, and multiple proteins can be detected when the sample is run on an SDS polyacrylamide gel. What does this tell you about the protein? A. The primary structure of the protein contains multiple cysteine residues that are hydrolyzed by the chemical reductant.
B. choline C. phosphatidylcholine D. fatty acid and triglyceride E. sphingomyelin - correct answer ✅B. choline Which of the following is false? A. Phospholipids are important in membrane structure. B. Phospholipids are amphipathic. C. Serine is a molecule that may be part of a phosphoglyceride. D. Phosphatidic acid contains two fatty acids and a phosphate group. E. Sphingolipids are the predominant phospholipid in membranes. - correct answer ✅E. Sphingolipids are the most predominant phospholipid in membranes; Explanation: phosphoglycerides are the most predominant phospholipids in membranes, not sphingolipids. In the lipid signals of phosphatidylinositol 4, 5-biphosphate (PIP2) is cleaved by _________ into two products: _________ and _________. A. phospholipase D; IP3; TAG
B. phospholipase C; IP3; DAG C. phospholipase D; IP3; DAG D. phospholipase C; IP3; TAG - correct answer ✅B. phospholipase C; IP3; DAG Of the following molecules, which would you predict diffuses most readily across membranes? A. hydrogen ions B. water C. glucose D. oxygen E. serine - correct answer ✅D. oxygen; Explanation: molecules that are small have an easier time diffusing. The composition of lipids in the outer and inner monolayers of cell membrane lipid bilayers is: A. asymmetrical; i.e. different in each monolayer. B. identical in each monolayer C. twice as concentrated in the inner monolayer as in the outer monolayer.
C. composed primarily of hydrophobic amino acids D. amphipathic - correct answer ✅D. amphipathic; Explanation: the transmembrane segment cannot be amphipathic because it is BETWEEN the bilayers, so it has to be hydrophobic. You are interested in the mobility of two different unknown integral plasma membrane proteins—protein X and protein Y—in a cell. In one cell, you fluorescently label all the X proteins. In another cell, you label all the Y proteins. When you perform FRAP (fluorescence recovery after photobleaching) analysis on both cells, you find that most of the protein X fluorescence has recovered within 3 minutes, but recovery of the protein Y fluorescence is significantly slower. Even after 10 minutes, only 50% of the protein Y fluorescence has recovered. What do these results tell you about proteins X and Y? A. Rapid recovery of protein X fluorescence indicates that protein X diffusion is constrained, perhaps because it is associated with other protein complexes. B. The slower and incomplete recovery of protein Y fluorescence indicates protein Y synthesis and trafficking are delayed.
C. Rapid recovery of protein X fluorescenc - correct answer ✅C. Rapid recovery of protein X fluorescence indicates that protein X readily diffuses in the plasma membrane. The Lactoperoxidase assay labels the exposed regions of membrane proteins as shown above. Lactoperoxidase (LP) is too big to diffuse through the lipid bilayer. However, if membranes are broken by sonication, then Lactoperoxidase can label the exposed regions of membrane proteins on both sides of the lipid bilayer. When you label intact cells with Lactoperoxidase, then extract the proteins and examine them, you find that several membrane proteins are labeled. When you break the cells by sonication, you find that many more proteins are labeled. Briefly explain how this is possible. - correct answer ✅Only some of the membrane proteins extend all the way through the membrane and have exposed regions on the outer surface. Many membrane proteins have exposed regions on the inner surface of the membrane, allowing those to be labeled after sonication. Smooth ER membranes form ________ structures. A. flattened sheet B. thin fiber C. large flattened sac
The flow of lipids and proteins through the Golgi can be depicted by: A. only the stationary and cisternae model B. only the cisternal maturation model C. the receptor endocytosis model D. both the stationary cisternae model and the cisternal maturation model. - correct answer ✅D. both the stationary cisternae model and the cisternal maturation model. A protein you are studying is encoded by a nuclear gene and is constitutively secreted from cultured HeLa cells. Therefore, this protein must be transiently found in ______. A. anterograde transition vesicles B. retrograde transition vesicles C. lysosomes D. smooth ER - correct answer ✅A. anterograde transition vesicles Which of the following is/are small GTPase(s)? A. Ras B. Rab proteins
C. ARF
D. All of the above - correct answer ✅D. all of the above Rab GTPases play important regulatory roles in membrane trafficking. You are studying a new GTPase, Rab36F, and its role in cancer. You find that the cancer cells you are studying have mutations in the GAP of Rab36F, such that the mutant GAP can no longer catalyze the inactivation of Rab36F. What do you predict will be the outcome of the GAP mutations? A. There will be a decrease in active Rab36F. B. Exchange of GDP for GTP on Rab36F will be impaired. C. There will be excess active Rab36F. D. GTP levels in the cytoplasm will decrease. - correct answer ✅C. There will be excess active Rab36F; Explanation: If the inactivation of Rab36F can no longer be catalyzed by GAP, then the GTPase will never be inactivated, causing an excess. Clathrin is involved in: A. anterograde transport from the ER to the Golgi B. retrograde transport from the Golgi back to the ER C. receptor-mediated endocytosis
Both MG132 and Bortezomib effectively inhibit protein degradation. Which of the following is the target of MG132 and Bortezomib? A. ubiquitin-activating enzyme (E1) B. ubiquitin-conjugating enzyme (E2) C. ubiquitin ligase (E3) D. ribosome E. proteasome - correct answer ✅E. proteasome How many Americans are affected by cancer each year? - correct answer ✅1.7 million How many Americans are KILLED by cancer each year? - correct answer ✅600, What percentage of cancer case have no known cause at all? - correct answer ✅40% Tumor - correct answer ✅An abnormal mass of tissue that forms when cells outgrow and out divide compared to normal cells.
Cancer - correct answer ✅Malignant tumor cells that invade and spread to other sites; result of uncontrolled cell division. What is the function of somatic cells in multicellular organisms? - correct answer ✅To support germ cells How do multicellular organisms arise? - correct answer ✅Arise from a single cell by cell division and differentiation. Mutations - correct answer ✅Errors that occur during DNA replication. What are some examples of mutations? - correct answer ✅Stalled replication forks due to DNA damage, and excessive compacting of chromatin. What are some sources of exogenous DNA damage? - correct answer ✅Cosmic rays, X-ray and UV radiation, and carcinogens
Tumor progression stage - correct answer ✅Once a tumor has formed, the tumor grows and proliferates; selection will favor cells that exhibit enhanced growth rate and invasive properties; at each stage of progression, some individual cell acquires an additional random mutation or epigenetic change that gives it a selective advantage over its neighbors. Intratumor heterogeneity - correct answer ✅Mixture of genetically distinct regions in a single tumor. List the 7 traits of cancer cells. - correct answer ✅Self-sufficiency in growth signals, insensitivity to anti-growth signals, evasion of apoptosis, limitless replicative potential, sustained angiogenesis, tissue invasion and metastasis, and genomic instability. What can cause cancer? - correct answer ✅Environmental agents, lifestyle factors, heredity, infectious agents.
What do many carcinogens share a need for before they can cause cancer? - correct answer ✅Metabolic activation Ames test for mutagenicity - correct answer ✅Bacteria are placed in a culture dish with media lacking histidine, along with the chemical to be tested. If the chemical is mutagenic, it will trigger random mutations. Some of the mutations will restore the ability to produce histidine, and the cells with these mutations will be able to form a colony on the medium. Function of enzymes - correct answer ✅Catalysis Function of regulatory proteins - correct answer ✅Cellular functions Function of signal proteins - correct answer ✅Cell-to-cell communication
