All Quiz 2 Questions 092309

All Quiz 2 Questions 092309 - Question 1 a. (1 point) For...

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Question 1 a. (1 point) For each of the following properties, answer whether the statement is true for microtubules, actin, or both. i. it is involved in a cell moving around within a tissue ii. it has a (+) end and a (-) end b. (2 points) You are interested in the regulation of the location of organelles within a cell, and decide to study the novel motor protein MOT1. In wildtype cells, the Golgi localizes immediately adjacent to the centrosome, which acts as the microtubule organizing center. In mot1- / mot1- cells, the Golgi is located farther away from the centrosome. What type of motor protein (dynein, kinesin, or myosin) is MOT1 most likely to encode, and why? c. (2 points) High resolution structural data allows you to determine that the distance between the two “heads” of MOT1 is 20 nm. You label one head of MOT1 with a fluorophore and perform single molecule measurements of MOT1 moving along the cytoskeleton. You get the following graph of MOT1 dynamics: Is the mechanism of MOT1 movement “inchworm” or “hand over hand”? Explain the reasoning for your answer.
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Question 1 a. (1 point) For each of the following properties, answer whether the property is true for microtubules, actin, or both. i. it is used as a track for kinesins ii. it is involved in muscle contraction b. (2 points) You discover a novel protein, MAP10, that binds to the (+) end of microtubules. Additionally, you note that in map10 - / map10 - mutant cells, the microtubules are present near the spindle poles during metaphase but don’t reach the chromosomes in the middle of the cell. What is the probable wildtype function of MAP10, and what is a possible mechanism for this function? c. (2 points) You next create an in vitro reconstituted system by adding purified centrosomes, tubulin, and MAP10 to cytosol extracted from frog eggs on a microscope slide. You are excited to see a difference in microtubule structures when wildtype MAP10 is added versus when mutant MAP10 is added. The wildtype structures are drawn for you. Draw the microtubule structures that forms when mutant MAP10 is added, and label the (+) and (-) ends. wildtype MAP10 mutant MAP10
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Question 2 a.) (2 points) Cohesins are important to keep sister chromatids together after s-phase. Explain the differences in the regulation of Cohesins in mitosis versus meiosis. b.) (3 points) On the following diagram label the kinetochore, centromere and cohesins. Why are the centromere and kinetochore important during mitosis? What protein is important for this in budding yeast? 1 2 3
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Question 2 a.) Kinesin 13 promotes the destabilization of microtubules and XMAP215 promotes plus-end microtubule assembly. Normally, Kinesin 13 is active throughout the cell cycle, but XMAP215 is not active during mitosis, which results in microtubule disassembly. After mutagenizing cells, you notice that when you observe microtubule dynamics in a
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All Quiz 2 Questions 092309 - Question 1 a. (1 point) For...

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