HW 3 Spring 2015 Chpts 10 12 13 14 3 4 1 Which of the following is are not involved in signal transduction A G protein coupled receptors B thyroxine T4 C epinephrine D RTKs receptor tyrosine kinases E A and D select E if both A and D do not require signal transduction 2 Which of the following is NOT involved in the signal processing of enzyme linked receptors A phosphorylation cascade B Ras G protein C signaling molecule D second messenger E B and D select E if neither B nor D are involved 3 Put the steps of the process of G Protein coupled signal receptors in the order they occur 1 A conformational change in the signal receptor complex activates an enzyme 2 Protein kinases are activated 3 A signal molecule binds to a receptor 4 Target proteins are phosphorylated 5 Second messenger molecules are released A 3 1 2 4 5 D 1 2 5 3 4 B 3 1 5 2 4 E 1 2 5 4 3 C 3 2 4 1 5 4 Which of the following is characteristic of steroid hormone action A protein phosphorylation B cell surface receptor binding C second messenger activation D internal receptor binding E transduction 5 The activation of receptor tyrosine kinases is characterized by A dimerization and IP3 binding B dimerization and phosphorylation C a phosphorylation cascade D GTP hydrolysis E channel protein shape change 6 Some disease causing microbes attack the body by turning on or off specific signal transduction pathways In the disease cholera the bacterium Vibrio cholera causes massive diarrhea by interfering with such a pathway In a person with cholera a toxin from this bacterium enters intestinal cells and chemically modifies G proteins Once modified the G proteins can no longer cleave GTP into GDP hence no phosphate group is removed from the G protein What would you predict will happen inside intestinal cells of a person with cholera A The membrane receptor will be continually activated B The G proteins cannot become activated and cannot activate the nearby enzyme adenylyl cyclase to make second messenger C The G proteins remain activated and will continually activate the nearby enzyme adenylyl cyclase to produce more second messenger D The G protein subunits cannot separate from each other hence no response is triggered E The G protein will continually trigger a phosphorylation cascade via receptor tyrosine kinases 7 The hormone adrenalin also known as epinephrine involves G protein coupled receptors It affects heart and liver cells differently It affects heart by increasing the heart rate whereas it affects liver by increasing its release of glucose Which of the following BEST describes how the same molecule can trigger such different responses A The activated receptors in heart and liver cells trigger different signal transduction pathways and hence lead to different cellular responses B In one instance the signal is processed directly where as in the other transduction of the signal results in a different response C Receptors for the hormone are different in each situation resulting in greater signal amplification in one situation as compared to the other D In one instance the physical form of the signal changes between the outside of the cell and the inside whereas in the other it does not E In one instance the signal triggers a sequence of phosphorylation events inside the cell whereas in the other it does not 8 Some cells have several nuclei per cell How could such multinucleated cells be explained A The cell underwent repeated cytokinesis but no mitosis B The cell underwent repeated mitosis with simultaneous cytokinesis C The cell underwent repeated mitosis but cytokinesis did not occur D The cell had multiple S phases before it entered mitosis E Transformation using plasmids that import nuclei 9 At which phase are centrioles beginning to move apart in animal cells A telophase D metaphase B anaphase E prophase C prometaphase 10 During which phase of mitosis do the chromatids become chromosomes A telophase D metaphase B anaphase E cytokinesis C prophase 11 Which of the following does NOT occur during mitosis A condensation of the chromosomes B replication of the DNA C separation of sister chromatids D spindle formation E separation of the spindle poles 12 Measurements of the amount of DNA per nucleus were taken on a large number of cells from a growing fungus The measured DNA levels ranged from 3 to 6 picograms per nucleus In which stage of the cell cycle did the nucleus contain 6 picograms of DNA D G2 A G0 B G1 E M C S 13 After telophase I of meiosis the chromosomal makeup of each daughter cell is A diploid and the chromosomes are each composed of a single chromatid B diploid and the chromosomes are each composed of two chromatids C haploid and the chromosomes are each composed of a single chromatid D haploid and the chromosomes are each composed of two chromatids E tetraploid and the chromosomes are each composed of two chromatids 14 Sister chromatids separate from each other during A mitosis only D mitosis and meiosis I B meiosis I only E mitosis and meiosis II C meiosis II only 15 When is mitosis NOT the M phase complete A Once cytokinesis is complete B Once the sister chromatids separate C Once the chromosomes begin to de condense D Once two daughter cells have formed E Once two independent nuclei have formed 16 How does MPF M phase promoting factor assist with a check point during the M phase A Removal of the inactivating phosphate from MPF is blocked if the DNA is damaged or if chromosomes are not replicated properly B The presence of MPF prevents the cells from splitting the chromatids until all kinetochores attach properly to the spindle apparatus C The presence of MPF activity prevents the cells from undergoing cytokinesis and exiting the M phase D DNA replication will not occur in the presence of MPF E In the absence of MPF cells enter the G0 state Use the following information to answer the two questions below The unlettered circle at the top of the figure shows a diploid nucleus with four chromosomes that have not yet replicated There are two pairs of homologous chromosomes one long and the other short One haploid set is black and the other is gray The circles labeled A to E show various combinations of these chromosomes 17 Which of the nuclei shown IN THE ABOVE FIGURE represents the chromosomes as they would be after meiosis I A A D D B C E E C C D 18 IN THE ABOVE FIGURE which cell s are haploid and what does n equal when considering haploid diploid in this example A Only A n 2 D B E n 4 B A C n 2 E D n 4