2006 Exam 3

2006 Exam 3 - NAME: _KEY_ MIDTERM EXAM III BIOLOGY 231 8...

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NAME: ____________ KEY _______________ MIDTERM EXAM III BIOLOGY 231 8 November 2006 ________________________________________________________________________________ -1- GENERAL INSTRUCTIONS: 1. Answer all questions IN INK, and do not use white-out if you anticipate requesting a re-grade. 2. No calculators. 3. 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. 4. SHOW YOUR WORK. SHOW ALL CALCULATIONS. 5. Make sure that your name is PRINTED LEGIBLY on EACH PAGE. 6. This exam consists of 7 questions on 12 pages and it is worth a total of 100 points. Information that might be useful: ! Use this convention for numbering the residues of a protein: label the first (most N-terminal) residue of the mature protein as “1", then number residues consecutively to the C-terminus. If an N- terminal signal sequence is removed during synthesis, re-number the residues starting with the new N-terminus = 1. ! A hydrophobic signal sequence can be a start-transfer or stop-transfer sequence depending on its position in the polypeptide. ! “Codon number” refers to how many codons away from the AUG you are in an mRNA (with the first AUG = #1). “Residue number” refers to how many amino acid residues away from the N–terminus you are in a protein (with the N–terminal aa = #1). ! An oligomer is a very small polymer, formed by the assembly of a small number of monomeric subunits. ! On this day, 8 November, in 1895 German physicist Wilhelm Conrad Rontgen made the first observation of x-rays, the portion of the EM spectrum with wavelengths 10 3 x shorter than visible light. His subsequent experiments with x-rays revolutionized medicine and won him the 1901 Nobel Prize.
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NAME: ____________ KEY _______________ MIDTERM EXAM III BIOLOGY 231 8 November 2006 ________________________________________________________________________________ -2-
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NAME: ____________ KEY _______________ MIDTERM EXAM III BIOLOGY 231 8 November 2006 ________________________________________________________________________________ -3- (1) You have cloned the gene for a membrane protein, the Lilly Channel, and predicted the amino acid sequence encoded by its mRNA. You find that the sequence contains four stretches of mainly hydrophobic residues, which you believe to be start and stop-transfer sequences. You work out their locations and codon numbers and arrive at the diagram of mRNA shown above. (a) 8 pts. Predict how the Lilly Channel will be organized in the membrane. DRAW it below as it will be arranged in the ER membrane after translation. In your drawing, LABEL the protein’s N-terminus, C-terminus, and the residue numbers at both boundaries of each membrane-spanning domain. Take care in your numbering. NOTE the labels for the sides of the membrane provided:
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2006 Exam 3 - NAME: _KEY_ MIDTERM EXAM III BIOLOGY 231 8...

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