Midterm 2021-No answers

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University of Calgary *

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403

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Jan 9, 2024

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Midterm Exam CMMB 403 University of Calgary October 18, 2021, 6:00-8:00 PM Rooms: ST-140/141 Time allowed: Two hours Name: ____________________ Please keep your answers to the space provided. No electronic aids of any kind may be used. Write your ID number on each of the following pages. This is important if pages get detached. Please answer the multiple-choice questions on the scantron sheet . Select the one BEST answer for each question. The 40 multiple-choice questions are each worth 1 point. Answer the six written questions (worth six points each) directly on the exam. 76 total points for the exam . Be sure your exam has 46 total questions. Cheating will not be tolerated

UC ID # __________________________ CMMB 403 Midterm #1 2 Multiple Choice (One point each) 1. How does dimerization of the Prolactin receptor lead to phosphorylation of STAT transcription factors? A. Dimerization activates the kinase activity of the prolactin receptor (a receptor tyrosine kinase) which phosphorylates STATs. B. Dimerization activates RAS which activates JAK kinases that phosphorylate STATs. C. The JAK kinase is a domain of the prolactin receptor protein (part of the same polypeptide chain); the JAK kinase domain is activated by dimerization and phosphorylates STATS. D. Dimerization activates the JAK kinases that are separate proteins that are associated with the cytoplasmic domains of the receptors. JAK kinases then phosphorylate STATs. 2. APC is the most commonly mutated gene in colon cancer tumors. Why does losing the function of APC promote tumor growth? A. The APC protein is necessary for the degradation of beta-catenin in the absence of a WNT ligand. B. The APC protein is a WNT ligand. C. The APC protein prevents the the degradation of beta-catenin in the absence of a WNT ligand. D. Loss of APC causes excessive cell proliferation in the colon. E. A and D 3. If a mouse embryo had a homozygous deletion of the smoothened gene, how would the hedgehog pathway be impacted? A. The pathway would be hyper-activated since smoothened is a repressor of the pathway. B. The hedgehog pathway would be inactivated even if ligands are bound to patched, since smoothened is required for the downstream events that prevent GLI proteins from being cleaved. C. The hedgehog pathway would not be affected since downstream components of the pathway would be intact. D. The pathway would be hyper-activated since smoothened activates the proteins that cleave GLI proteins. 4. Why can you conclude that the somatic cells of the ovary must express LGR proteins? A. The ligand for LGR proteins are WNTs, and WNTs are required for female sex determination. B. RSPO1 is a ligand for LGR proteins, and RSPO1 is required for female sex determination. C. The ligand for LGR proteins is APC, and APC is required for female sex determination. D. LGR proteins are receptors for DELTA proteins. 5. The technique of cloning by somatic cell nuclear transfer (SCNT) relies on ________________ to reprogram a differentiated cell to a totipotent/pluripotent state. A. an electric pulse. B. the expression of four defined factors C. the cytoplasm of a highly proliferative differentiated cell D. the cytoplasm of the oocyte (egg)

UC ID # __________________________ CMMB 403 Midterm #1 3 6. Where would you expect to find SRY expression in an adult human testis? A. the Sertoli cells B. the germ cells C. the Leydig cells D. nowhere, SRY is not expressed in adults 7. The FGFR3 receptor A. can only activate the JAK-Stat pathway B. is a receptor tyrosine kinase: therefore, it only functions through the classical RAS-ERK pathway. C. is a receptor tyrosine kinase that signals through the classical RAS-ERK pathway, but it can also activate the JAK-STAT pathway. D. is an inhibitor of he classical RAS-ERK pathway since it is a negative regulator of skeletal growth. E. is a non-receptor tyrosine kinase found in the cytoplasm. 8. How could any of the following probes be used in an in situ hybridization experiment to determine if an E12.5 genital ridge is from a male or a female mouse? A. A Cyp26b1 probe would stain the male genital ridge and not the female. B. A Cyp26b1 probe would stain the female genital ridge and not the male. C. A Sox9 probe would stain the female genital ridge and not the male. D. An Oct4 probe would stain only the female genital ridge. E. An Oct4 probe would stain only the male genital ridge. 9. What does it mean that an enhancer acts in cis to activate a gene? A. The enhancer is on a different chromosome than the gene it activates. B. The enhancer is on the same chromosome as the gene it activates. C. The gene coding for a transcription factor that activates the gene is on the same chromosome as the enhancer. D. This means that the enhancer must make contact with the promoter of the gene it activates. 10. Why do males normally NOT have oviducts and a uterus? A. They never develop a Mullerian Duct, the precursor of oviducts and uterus. B. The somatic cells of their gonads don't have nuclear beta-catenin, which is necessary for the Mullerian duct to form. C. Their gonads produce testosterone which causes the mullerian duct to degenerate. D. Their developing Sertoli cells produce a TGF-beta superfamily ligand that actively causes the Mullerian duct to degenerate.

UC ID # __________________________ CMMB 403 Midterm #1 4 11. Which of these proteins is a transcription factor that binds to the anti-mullerian hormone ( AMH ) gene's promoter and activates its transcription? A. SRY B. RSPO1 C. SOX9 D. WNT4 E. PAX6 12. If you wanted to remove all canonical WNT signaling from mice, but leave the planar cell polarity pathway intact, the easiest and most effective strategy would be to A. mutate/knockout the gene coding for beta-catenin. B. mutate/knockout all the genes coding for WNT ligands. C. mutate/knockout the gene(s) coding for Disheveled. D. mutate/knockout all genes coding for R-spondin proteins. E. mutate/knockout all genes coding for Frizzled receptors. 13. Where can beta-catenin be located in a cell? Choose the BEST answer. A. Bound to the intracellular domain of cadherins. B. In the cytoplasm C. In the nucleus D. B and C E. A, B and C F. None of the above, beta-catenin is secreted outside the cell 14. What would you predict would be the phenotype in the gonads of mice that have a homozygous-null mutation of the Cyp26b1 gene? A. In females, germ cells would prematurely enter meiosis during embryonic/fetal development. B. In both sexes, germ cells would prematurely enter meiosis during embryonic/fetal development. C. In males, germ cells would prematurely enter meiosis during embryonic/fetal development. D. In females, germ cells would be delayed in their entry into meiosis. E. In males, germ cells would be delayed in their entry into meiosis. 15. Why is it impossible for the DELTA protein to function as a morphogen? A. it is an entirely intracellular protein so it cannot diffuse to form a gradient. B. it is a transmembrane protein, anchored to the cell membrane, so it cannot diffuse to form a gradient. C. it is a transmembrane protein, anchored to the cell membrane, so it cannot be involved in cell to cell signalling. D. these ligands cannot affect cell differentiation. E. it is a nuclear protein

UC ID # __________________________ CMMB 403 Midterm #1 5 16. Examine the three locations marked on this drawing of a crypt within the small intestine epithelium. Among these choices, where would you expect to find the highest amount of phosphorylated SMAD1/5 proteins to be present? A. Location #1 B. Location #2 C. Location #3 D. phosphorylated SMAD1 /5 would be found at similar levels in all three locations. 17. By examining the same image of an intestinal crypt as in question #16, where would you expect to find the highest amount of the highest amount of a receptor for R-spondin proteins to be present? A. Location #1 B. Location #2 C. Location #3 D. this receptor would be found at similar levels in all three locations. 18. Which of the following is (are) a paracrine factor(s) necessary for induction of the lens of the eye in vertebrates? A. BMP4 B. SOX2 C. PAX6 D. All of the above E. A and B 19. How would treatment of cultured cells with an inhibitor of the GSK3 protein influence a paracrine signaling pathway? A. It would activate the planar cell-polarity pathway B. It would activate canonical WNT signaling. C. It would inhibit canonical WNT signaling. D. It would activate sonic hedgehog signaling. E. It would inhibit sonic hedgehog signaling.

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