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Lecture 18

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Department
Psychology
Course
PSYC12H3
Professor
Gerald Cupchik
Semester
Winter

Description
Lecture 18 Quiz Question 1 - 549 Which one of the following is correct about Cytokinesis: Cytokinesis leads to segregation of duplicated chromosomes into daughter nuclei The first hint of cytokinesis in animal cells apears in metaphase. A cell plate a formed during cytokinesis of an animal cell The mechanism of cytokinesis in animal cells is in an opposite direction of that of plant cells Both A and D are correct Question 2 - 534 which of the following events DOES NOT promote the metaphase-anaphase transition? FIGURE 14.26 (b) The APC binds Cdc20 and ubiquinates securin. An active protease called separase is released . Cdh1 binds APC ubiquinates anaphase inhibitor which is called securin Separase cleaves cohesins that hold sister chromatids together. anaphase begins when sister chromatids separate. Question 3 - 531 Which of the following statements is/are incorrect? During anaphase, sister chromatids lose affinity for each other During metaphase, chromosomes move away from poles via kinesin activity During prometaphase, chromosomes move toward poles via dynein activity. During cytokinesis, microfilaments are involved in the formation of the contractile ring None of the above are incorrect. Question 4 - 536 Animal cells and plant cells go through cytokinesis through different mechanisms. Which of the following is/are true regarding cell cytokinesis? Plant cells conduct cytokinesis through an inside to outside mechanism Plant cells conduct cytokinesis through an outside to inside mechanism Animal cells conduct cytokinesis through an outside to inside mechanism Animal and plant cells conduct cytokinesis through an inside to outside mechanism Both A and C Question 5 - 513 Which of the following are false concerning the phragmoplast? A phragmoplast uses an inside-out mechanism to form the cell plate It involves the microtubule association to vesicles It occurs during in late cytokinesis It only appears in plant cells All of the above are true Which statement(s) below regarding the Metaphase Spindles of an Animals cell are true? (reference: slides 3-4 on lecture 18, and pages 578 + 586) Astral Microtubules help position the spindle apparatus in the cell and may help determine the plane of cytokinesis. Kinetochore microtubules exert a pulling force on the kinetochores of the chromosome, which results in the chromosomes being maintained at the equatorial plane. Kinesins use polar microtubules for the initial movement of spindle poles away each other in prometaphase. All of the above. A and B only Question 2 - 509 Which of the following statement is true? Levels of APCCdh1 are high from Anaphase to G1. Levels of APCCdh1 are low from Anaphase to G1. Level of APCCdc20 is high during the S and G2 phases of the cell cycle. Level of APCCdh1 is high during the S and G2 phases of the cell cycle. Both A and C Question 3 - 514 Which of the following occurs in anaphase B movement? The sister chromatids move towards the poles The poles separate with a dynein-like motor acting on the polar microtubules The chromosomes move toward the pole due to dynein-like motors The dynein-like motor pulls the spindle poles to the cell cortex None of these Question 4 - 535 which of the following options are correct? astral microtubules position mitotic spindle and determine plane of cytokinesis. polar microtubules associates with pole separation. kinetochore microtubles divides the cell's cytoplasm in to two packages. a and b are correct. b and c are correct. Question 1 - 504 Which of the following is an incorrect statement about anaphase? Opposite spindle poles separate in Anaphase B via the activity of a kinesin-like motor A kinesin-like motor is associated with the cell cortex and acts to pull spindle poles apart by acting on polar microtubules Sister chromatids lose affinity for one another Sister chromatids move towards opposite poles in Anaphase A due to the activity of a dynein-like motor Different molecular motors are required as well as the destruction of some regulatory molecules B: Incorrect. It is a DYNEIN-like motor which associates with the cell cortex, not a kinesin-like motor. Also, astral microtubules are operated on, not polar. See figure 14-33 in the textbook for additional clarification. Question 2 - 531 Which of the following statements is/are incorrect? During anaphase, sister chromatids lose affinity for each other During metaphase, chromosomes move away from poles via kinesin activity During prometaphase, chromosomes move toward poles via dynein activity. During cytokinesis, microfilaments are involved in the formation of the contractile ring None of the above are incorrect. Question 3 - 546 Which of the following would allow anaphase to take place? Mad binds to Cdc20, preventing APC from destroying securin Mad binds to Cdc20, allowing APC to destroy securin Mad binds to Cdh-1, preventing APC from destroying securin Mad2 is lost, preventing the securin to be destroyed Mad2 is lost, securin is destroyed Question 4 - 503 During anaphase, which of the following events occurs first in order for a normal, non-mutant cell to complete the phase? Proteasome breaks down ubiquitinated separase (protease) Cleavage of cohesins lead to inactivation of CDK (MPF) sister chromatids attach to spindle poles Securin(anaphase inhibitor) is ubiquitinated Separase cleaves Cohesins, allowing sister chromatids to segregate Question 1 - 533 When APC/cdh1 levels are high in a cell: The cell is in metaphase of mitosis Then APC/cdc20 levels in the same cell are also high Then the cell is exiting mitosis and entering the G1 phase This will activate CDK, causing the cell to stop division Both b and d are correct Question 2 - 541 Which of the following statements about anaphase is false? Anaphase A involves the poleward movement of sister chromatids due to activity of a dynein motor As securin is targeted for destruction, its binding partner separa
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