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2009 Exam 4 - NAME EXAM IV BIOLOGY 231 14 December 2009...

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NAME: _______________________________ EXAM IV BIOLOGY 231 14 December 2009 ________________________________________________________________________________ -1- GENERAL INSTRUCTIONS: 1. Answer all questions legibly and concisely. 2. Confine each answer to the BOX or SPACE provided. Only what is clearly written in the box or space will be graded! Use the back of the pages for “rough drafts” if you like. 3. SHOW YOUR WORK where appropriate. 4. Make sure that your name is PRINTED LEGIBLY on EACH PAGE. 5. This exam consists of 8 questions on 13 pages and it is worth a total of 100 points. WE WILL NOT OFFER RE-GRADING ON THIS EXAM. If you like, you can pick it up in LILY G-108 after 12/21/09. All unclaimed exams will be shredded on 1 Feb 2010. 6. Have a happy and safe holiday. Information that may be useful: ! Myosin motor proteins translocate along the surface of actin filaments, toward the plus end. ! The major motor proteins that translocate along microtubules are dyneins and kinesins. MT = abbreviation for “microtubule.” ! In the mitotic spindle, kinetochore MTs interact with chromosomes, while polar MTs interact with polar MTs from the opposite half-spindle. Astral microtubules extend toward the cell cortex. ! On this day in 1911, Norwegian explorer Roald Amundsen and his team of 5 men and 16 sled dogs became the first to reach the South Pole of our planet.
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NAME: _______________________________ EXAM IV BIOLOGY 231 14 December 2009 ________________________________________________________________________________ -2- (1) 5 pts. A “sizes” question. NUMBER each of the following molecules or structures in order such that 1 is the LARGEST and 5 is the SMALLEST . In other words, 5 is the SMALLEST and 1 is the LARGEST : ____ 3 ___ MPF (maturation promotion factor) ____ 1 ___ Sir Paul Nurse, 2001 Nobel Prize winner ____ 4 ___ a cyclin molecule ____ 5 ___ a phosphate group ____ 2 ___ a bacterium
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NAME: _______________________________ EXAM IV BIOLOGY 231 14 December 2009 ________________________________________________________________________________ -3- (2) You have analyzed the polymerization and depolymerization of actin filaments under experimental conditions that allow you to determine independently the behavior of the plus and minus ends. After determining these rates over a broad range of [actin], you plot the concentration vs rate and obtain the graph at right. Study this graph and answer the following questions: (a) 1 pt. What is the critical concentration for assembly at the plus end? (b) 1 pt. What is the critical concentration for assembly at the minus end? (c) 2 pts. Exactly what would occur for the average filament if you placed them into a solution where the initial free [actin] = 0.15 M? They would shorten by disassembly at BOTH ends. (d) 2 pts. Exactly what would occur for the average filament if you placed them into a solution where the initial free [actin] = 1.9 M? They would grow by assembly at BOTH ends. (e) 3 pts. Exactly what would occur for the average filament if you placed them into a solution where the initial free [actin] = 0.7 M? They would treadmill, with assembly at + end and disassembly at end. 0.25 ì M 1.0 ì M
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NAME: _______________________________ EXAM IV BIOLOGY 231 14 December 2009 ________________________________________________________________________________ -4- (3) 10 pts. The two diagrams below represent a cross-section of the ciliary axoneme and an “overhead” view of the lamellipodium, as we saw them in lecture, text and problems sets. On these diagrams, identify the structure associated with each function listed in the left column of the table, and enter the appropriate letter(s) in the right column.
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