MidtermSamples

MidtermSamples - Bio200A: Quarter 2 Haverford College, Fall...

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Bio200A: Quarter 2 Haverford College, Fall 2007 Andrea Morris, PhD The questions below cover the following topics: translation; post-translational modifications; protein translocation and targeting; cell signaling and the cell cycle and its regulation. These questions are meant to serve as examples of the types of problems you will be asked to solve on the Midterm Celebration. QUESTION 1. The figure below shows the stage in translation when an incoming aminoacyl-tRNA has bound to the A-site on the ribosome. Using the components shown in the figure as a guide, show on part B and part C what happens in the next two stages to complete the addition of the new amino acid to the growing polypeptide chain. Figure 1.
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QUESTION 2. What would happen in each of the following cases? Assume in each case that the protein involved is a soluble protein, not a membrane protein. A. You add a signal sequence (for the ER) to the amino-terminal end of a normally cytosolic protein. B. You change the hydrophobic amino acids in an ER signal sequence into charged amino acids. C. You change the hydrophobic amino acids in an ER signal sequence into other, hydrophobic, amino acids. D. You move the amino-terminal ER signal sequence to the carboxyl-terminal end of the protein. QUESTION 3. The figure below shows the orientation of a multipass transmembrane protein after it has completed its entry into the ER membrane (part A) and after it gets delivered to the plasma membrane (part B). This protein has an amino-terminal signal sequence (depicted as the black membrane spanning box), which is cleaved off in the endoplasmic reticulum by signal peptidase. The other membrane-spanning domains in the protein are depicted as open boxes. Given that any hydrophobic membrane-spanning domain can act as either a start-transfer or a
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This note was uploaded on 04/07/2008 for the course BIOL 200 taught by Professor Morris during the Fall '07 term at Haverford.

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MidtermSamples - Bio200A: Quarter 2 Haverford College, Fall...

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