Q5. Each ionizable group of an amino acid can exist in one of two states, charged or neutral. The electric charge on the functional group is determined by the relationship between its pKa and the pH of the solution. This relationship is described by the Henderson-Hasselbalch equation. (a) Histidine has three ionizable functional groups. Write the equilibrium equations for its three ionizations and assign the proper pKa for each ionization. Draw the structure of histidine in each ionization state. What is the net charge on the histidine molecule in each ionization state? (b) Draw the structures of the predominant ionization state of histidine at pH 1, 4, 8, and 12. Note that the ionization state can be approximated by treating each ionizable group independently. (c) What is the net charge of histidine at pH 1, 4, 8, and 12? For each pH, will histidine migrate toward the anode (+) or cathode (-) when placed in an electric field?

1. Make a series (at least 3) of drawings to show the three dehydration synthesis reactions that take place between the two Fatty Acids, the Phosphate Head and the Glycerol.  Show the water molecules made. a) Label the following on the completed phospholipid: hydrophilic and hydrophobic parts of the molecule, fatty acids, phosphate group, and glycerol.   b) Compare the structure of the phospholipid to that of a triglyceride.  How are the two molecules Similar?  How are they different? 2. Use the following vocabulary to label and draw a cell membrane: cytoplasm (cell lumen) extra-cellular fluid hydrophobic hydrophilic polar head non-polar tails a) How many O-H groups are there? And are the O-H areas of sucrose polar or non-polar? b) What is the term that is used to discuss how tightly or loosely an atom's nucleus has a hold of its valence electrons?

2. | Calculate the overall charge (pH 7) on the following three polypeptides and answer the questions below. Assume the following pKa values: N-terminal –NH3®, 7.0; all -COOH groups, 4.0; Arg, 12.5; Cys, 8.4; His, 6.0; Lys, 10.0; Tyr, 10.0. (A) Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Lys–Pro–Val–Gly–Lys–Lys–Arg-Arg-Pro-Val-Lys–Val-Tyr-Pro-Asp-Ala -Gly- Glu-Asp-GIn– Ser-Ala-Glu-Ala-Phe-Pro-Leu-Arg-Glu-Phe (B) Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Ala-Pro-Val-Gly-Glu-Glu–Cys-Asp-Pro-Val-Glu–Val–Tyr-Pro-Asp- Ala-Gly-Glu-Asp-Gln-Ser-Ala-Glu-Ala-Phe-Pro-Leu-Glu-Phe-Cys-Ser-Tyr-Ser-Met-Glu–His-Phe-Asp-Trp-Gly- Asp-Pro-Val-Gly-Pro-Asp-Ala-Gly-Asp-Gln-Pro-Val–Gly–Glu-Glu-Cys-Asp-Pro–Val-Glu–Val–Tyr-Pro-Asp-Ala (C) Gly-Ser-Val-Arg-Asp-Pro-Val-Lys-Glu-Val-Tyr-Pro-Asp- Lys–Ala-Gly-Arg-Glu-Ser-Arg-Ala (d) Which of the three peptides would migrate the closest to the anode in isoelectric focusing? (e) Which of the above peptides would elute last from a gel filtration column? (f) Which of the three…

20. The dissociation constant of protein Z for ligand Y is: 10 micromolar. What fraction of the ligand is bound at ligand concentration = 5 micromolar?

Explain what the meaning of these distances is (e.g., from where to where?)Crystal structure of human monocyte chemotactic protein-2