Exam (elaborations) Biochemistry Final Exam

Biochemistry Final Exam 1) Calculate the enthalpy of formation per mol of NH3: Bond energies: H2, 436k KJ/mol; N2, 945 KJ/mol, N-H, 391 KJ/mol a) -93 KJ b) -1080 KJ c) 1080 KJ d) 45 KJ e) -46.5 KJ 2) Membrane structures are held primarily by? (OR membrane fs in a lipid bilayer are held together primarily by?) a) Hydrophobic interactions b) Covalent bonds c) Ionic Interactions d) All of the Above 3) Which system corresponds to the intracellular buffer in humans? a. H2PO4 -/ HPO4 2-/ PO4 3- system b. CO2/HCO3/H2CO3 system c. All of Above d. None of Above 4) Which of the following has the best buffering capacity? a. 2M CH3COOH/ 2M CH3COOb. 0.2M CH3COOH/ 0.2M CH3COOc. 7M CH3COOH/ 7M CH3COO- 5) Which of the following statements is incorrect about the following amino acids? a. Phe and Ala are nonpolar b. His and Arg are basic c. Cys and Gly are polar d. Asp and Asn are acidic 6) Which of the following amino acids belong to the same group? a. leu, pro, ala, val b. his, arg, lys, glu c. gly, tyr, cys, pro d. asp, glu, asn, gln 7) Determine the amino acid sequence of the following oligopeptide from the experimental data below: 1. the amino acid composition is found to be ala, lys, phe, met, cys, trp 2. treatment with carboxypeptidase results in tryptophan and a peptide 3. CNBr treatment yields a tetrapeptide and a dipeptide 4. Trypsin digestion produces and amino acid and a pentapeptide with met on the amino end 5. Chymotrypsin digestion yields a dipeptide and a tetrapeptide a. trp-lys-met-cys-met-ala b. lys-ala-cys-phe-met-trp c. trp-ala-phe-cys-met-lys d. lys-met-cys-phe-ala-trp 8) What is the overall net charge of the following polypeptide at pH = 13? lys-lys-his-glu a. +2 b. 0 c. –2 d. 1 9) Place the following amino acids by increasing isoelectric points: his, ala, asp, lys, arg. a. asp, ala, lys, arg, his b. his, lys, arg, ala, asp c. arg, lys, ala, his, asp 10) Most non-basic and non-acidic isoelectric amino acids: a. give a basic solution in water b. give an acidic solution in water c. give a neutral solution in water 11) Which cannot be a component in an alpha helix? a. lys b. gly c. pro d. All are components