Biotechniques in Biochemistry, PLEASE HELP! Calculate the final pH._ Draw the st
ID: 826557 • Letter: B
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Biotechniques in Biochemistry, PLEASE HELP!
Calculate the final pH._ Draw the structure of the following pentapeptide as it exists at pH 7. Draw each bond and hydrogen in the structure. threonylglutamylphenylalanylarginyllysine (thr-glu-phe-arg-lys) For the R groups in the pentapeptide listed in #3 above indicate whether it is a) acidic, basic, or uncharged; b) polar or nonpolar (hydrophobic); c) aromatic or nonaromatic. (Each group needs three labels.) What is the net charge of the major species of the peptide drawn in #3 above at a) pH=7 and b) pH=12? If a group carries a significant partial charge at the above pH's calculate the fraction in the charged form. Use the approximate pKa's given in the notes for all the side chain groups with acid/base properties as well as the alpha carboxyl and alpha amino groups on the C terminus and N terminus of the peptide. Note amide bonds -like the peptide bond and the side chains of glutamine and asparagine do not have a pK In general, chemical reactions happen faster at higher temperatures because: The high temperature hasn't reached the activation energy of the reaction At higher temperatures, molecules and ions move faster and are more likely to make contact with each At low temperatures, the molecules are frozen in place The catalysts denature at low temperature Catalysts are unaffected by temperature changes The major effect of a catalyst on a reaction is to: Keep the substrates apart Lower the equilibrium constant Raise the equilibrium constant Raise the activation energy Lower the activation energy Consider the reaction: ethyl acetate + H20 -> ethanol + acetic acid, the enzyme which catalyzes this reaction is classified as a/an: Oxidoreductase Transferees Hydrolase Lyase Isomerase The Bohr effect describes the affect of pH on binding of oxygen by hemoglobin. In general, this effect: Instructions: Please work independently, closed notes and book and the book and submit the test o Tuesday, April 1, 2014 at 6pm. Good Luck! a) Glycylglycine, a dipeptide, can be used as a buffer in solution. It is a good buffer near pH 3 and near pH 8. Which functional groups on this dipeptide can act as buffers and what are their pKs?_ A 0.1 M glycylglycine solution at pH 3.1 could act as a buffer. What percent of the carboxyl group would be in the ionized form?_What percent of the amino group would be in the ionized form?_Which functional group of glycylglycine is acting as a buffer in this solution?_(2 significant figures is sufficient). What would be the final pH of a 200mL solution of 100.0 mM histidine at pH 6 if one liter of (1.0 mM mmoles/liter) HCI was added? The pKa's of histidine are alpha carboxyl=1.82, imidazole = 6.0, and alpha amino =9.17. Diagram (using the histidine structure) the ionization reactions by which a functional group(s) on the histidine allow for the maintenance of a near constant pH. Which pK is to be used in this problem?_ What was the base/acid ratio of this group in histidine before the HCI was added? What are the total # of moles of histidine present?_ What were the moles of base form and acid form before and what were the moles after the HCI was added? Instructions: Please work independently, closed notes and book and the book and submit the test on Tuesday, April 1, 2014 at 6pm. Good Luck!Explanation / Answer
[1] pKa values of glycylglycine-- pK
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