Author: Anonymous

Is the bolded statement TRUE or FALSE? The predominant form of Glu at a pH of 3.0: 31. has a protonated side chain which has a neutral charge. 32. has a net +1 charge. 33. has a side chain capable of forming an ionic bond with the side chain of His at the same pH. 34. is classified as an acidic side chain. 35. will have a -1 charge when found in the middle of a peptide

Is the bolded statement TRUE or FALSE?   In class we spent a significant amount of time discussing the structural features of the peptide backbone.  Given this which of the following statement(s) is (are) true? 41. All conformations of the backbone are energetically equivalent. 42. Each amino acid can have at least two dihederal angles that, when changed, result in a new conformation for the peptide backbone. 43. Some phi/psi angles are not favored because they cause steric clashes in the backbone. 44. The cis configuration for the peptide bond, if adopted in the absence of a proline, will destablize the protein. 45. Formation of an alpha-helix requires backbone hydrogen bonding but NOT specific phi/psi angles adoption.

Short answer Instructions-   On this exam you must answer a single free response question.  The question is worth 10  points, be as concise as possible.     Stated below is the primary structure of a small peptide that is known to form an α-helix.  Using this sequence answer the following questions:   +H3N-RKMVDILKR-COO-   How many peptide bonds exist in this protein (1 point)? ___________ What would the charge of this α-helix be at pH 8.5 (assume pK’s remain constant)? (2 points) ___________ Using the diagram below, would you say that this helix is amphipathic? If your answer is yes, state the number (residue #1 or #2 for example) of the residues that are hydrophilic (assume R represents residue #1 in the diagram)? (3 points) ___________ Finally, if I were to replace the 5th amino acid with a K side chain would this have any effect on the formation of the helix at pH of 13? How about pH of 7? Why do you think so for both pH’s? (4 points)

Is the bolded statement TRUE or FALSE? Tertiary and quaternary structures are the final levels of protein structural hierarchy.  51. Subunits are held together by non-covalent forces to make up the quaternary structure of a protein. 52. The hydrophobic core of a globular protein forms when two subunits with hydrophobic interfaces come together. 53. Non-covalent interactions between amino acids side chains within a single tertiary structure only form between amino acids close to each other in the primary structure. 54. Quaternary structures can consist of no more than 7-subunits.55. The quaternary structure of a protein can be formed by subunits of identical primary structure or differing primary structures.

Is the bolded statement TRUE or FALSE? Hydrogen bond(s): 26. only form in polar solvents. 27. are interactions between dipoles that are formed (the dipoles) when atoms of differing electronegativity form covalent bonds. 28. formation is not important in protein folding as large numbers of hydrogen bonds must also be broken between the unfolded protein and the solvent. 29. when forming, can contribute to a negative change in enthalpy. 30. when forming, can contribute to a negative change in free energy.

In a recent study of 42 eighth graders, the mean number of hours per week that they played video games was 19.6 with a population standard deviation of 5.8 hours. Compute the 98% confidence interval for μ.

A pollster wishes to estimate the proportion of United States voters who favor capital punishment. How large a sample is needed in order to be 90% confident that the sample proportion will not differ from the true proportion by more than 4%?

Formation and maintenance of collagen requires

Below are the structures of  amino acids at pH 7. Match the numbered structure with the appropriate label. 6. 7.  8.  9.  10.   

Pneumothorax is: (pick all that apply)