Question

Biochem help 2

14. What would be the net charge on the dipeptide Ser-His at pH- 6.04? (Choose the one best answer.) a) 1.5 b) +1; c) +0.5 d) 0 e) -0.5; 15. The pKa of a lysine side chain in a protein ending up on the outside of a globular protein has a different pKa than if the lysine is buried within the interior of a protein. What would be the expected pKa of a side chain of lysine buried within the interior of a globular protein? (Choose the one best answer). e) 3 a) 12.5 b) 10.5 c) 8.8 d) 6.0 16. The investigator who is given credit for promoting the endosymbiotic theory of evolution is: (choose one best) d) Edwin Chargaff e) Emil Fischer a) Lyn Marg b) Rosalind Franklin c) Linus Pauling 17. A 10-mL solution has an Naci concentration of 0.45 M. This material is put in dialysis tubing and dialyzed against 1 liter of distilled water. At the end of this time, what is the concentration of Nacl in the dialysis bag? Assume no change in volume in the dialysis bag. Choose the one best and closest answer. e) 0.00044 M a) 4.4 M; b) 0.445 M; c) 0.044 M; d) 0.0044 M; 18. Which of the following would serve as the best buffer for a solution that must be maintained at pH 6.6. (Choose the one best answer) a) 0.10 M H2PO4 /HPO pK 7.2 b) 0.010 M HrPO4 /HPO42, pK 7.2; c) 0.010 M Hrco,/Hco, pk 6.4 d) 0.10 M Hicob/HCOs, pK 6.4 d) 0.10 M HoPO4/HaPoi, pK 2.14 the pl (isoelectric pH) the net charge of a peptide is positively charged and above the pl (isoelectric pH) the net charge of a peptide is negatively charged. At the pl a peptide or protein has a net charge of 0. Peptide A has a pl of 8.7. (Choose all correct answers). a) at pH 4.0 this protein will bind to an anion exchange column b) at pH 4.0 this protein will bind to a cation exchange column. c) at pH 10.8 this protein will bind to an anion exchange column. d) at pH 10.8 this protein will bind to a cation exchange column. size exclusion (gel filtration) column composed of gel with fractionation range 10,000 250,000 Da is used to attempt to separate a mixture of proteins composed of A: 55,000 Da B: 15,000 Da 100,000 D: 220,000: E: 300,000 Da What will be the order of elution of these proteins from this column? Choose the one best answer F: 400,000 Da a) First Fand E will elute together in void volume, then D, then c then A then B will elute b) First B then A then C then D then E then F c) First Band A will elute first and together, then C then D then E then F d) First F then E then C then B then A then D

Answer 1

Reason:

16. tigator who is given credit for promoting the endosymblotic theory of evolution is: (choose one best) Question-1 Lyn Margulis; b) Rosalind Franklin; c) Linus Pauling d) Edwin Chargaff e) Emil Fischer Reason: 1.vn Nirơnlis is the cell hinInơist яnd he nrnnnsed endnsvmhintie thenrv. 20. A size exclusion (gel filtration) column composed of gel with fractionation range 10,000 250,000 Da is use attempt to separate a mixture of proteins composed of A: 55,000 Da; B: 15,000 Da; What C: 100,000 Da; D: 220,000: E: 300,000 Da F: 400,000 Da the order of elution of these proteins from this column? Choose the one best answer First F and E will elute together in void volume, then D, then C then A then B will elute b) First B then A then C then D then E then F c) First B and A will elute first and together, then C then D then E then F d) First F then E then C then 8 then A then D

1. Size exclusion chromatography or SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis): This technique of purification based on protein size or molecular weight of the protein.

Princple of size exclusion chromatography if “adsorption”. Larger molecules with more molecular weight cannot pass through pores within the stationary phase and thereby they elute first followed by smaller molecules with low molecular weight as these molecules are bounded in the porous particles of polymer stationary phase.