midterm2006a - 2/1/06 ) Bio 98A Midterm Exam Name _ (4) _...

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2/1/06 Bio 98A Midterm Exam Name __________________________________________ ------------ ) For the following two ligands, what type of forces could be involved in their (4) ______ non-covalent binding to a protein's active site? (do not include van der Waals forces) leucine ionic or charge-charge or electrostatic, H-bonding , hydrophobic interaction glucose H-bonding ) The image shown here is a(an) (2) ______ micelle ) 10 mmols of NaH 2 PO 4 is dissolved in 423 ml of water. To bring the pH to 7.16, you could add (2) ______ 20 mmols of Na 2 HPO 4 . D = 7.16 - 6.86 = 0.30 = log R, R = antilog 0.30 = 1.995 ≈ 2.0 pH > pKa, so (mmol Na 2 HPO 4 ) / (mmol NaH 2 PO 4 ) = 2/1 = x/10 x = 20 mmol ) How many mmol of lactic acid must be added to 50 ml of water to make the pH=4.4? (2) ______ Ka = [H + ][A - ] / [HA] = [H + ] 2 / [HA] , [HA] = [3.98x10 -5 M] 2 / 1.39 x 10 -4 M = 1.15 x 10 -4 M Total lactate = [HA] + [A - ] = [HA] + [H + ] = 3.98x10 -5 M + 1.1 x10 -5 M = 5.13 x 10 -5 M 5.13 x 10 -5 mmol/ml x 50 ml = 256.5 x 10 -5 mmol = 2.57 x 10 -3 mmol 1 pt credit if answer assumes total lactate [HA] = 1.15 x 10 -4 M 1.15 x 10 -4 mmol/ml x 50 ml = 5.8 x 10 -4 mmol Sorry about this question - more complicated than I intended - but a few students did get the 1 pt answer. ) 100 pmol of the following peptide is subjected to automated Edman degradation in a sequencer that (2) ______ produces an average yield of 85% at each cycle. LASVEGAS Step 4 should produce 52.2 or 61.4 pmol of the amino acid valine . 0.85x0.85x0.85x0.85 = (0.85) 4 = 0.522 , 0.522 x 100 pmol = 52.2 pmol (Aswad's answer) 0.85x0.85x0.85 = (0.85) 3 = 0.614 , 0.614 x 100 pmol = 61.4 pmol (Lehninger answer)
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2/1/06 Bio 98A Midterm Exam Name __________________________________________ ------------ ) Complete the following for the peptide A-N-G-E-L-I-C-A (5) ______ a. molecular weight ______789_____ grams/mol b. net charge at pH 9.7
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This note was uploaded on 03/30/2009 for the course BIOCHEM 98 taught by Professor Mclaughlin,c during the Winter '09 term at UC Irvine.

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midterm2006a - 2/1/06 ) Bio 98A Midterm Exam Name _ (4) _...

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