Biochemistry final

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Biochemistry final
2013-12-11 01:50:23

biochemistry final
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  1. What should the tripeptide CDA show at pH 7?
    the three amino acids (Cys-Asp-Ala) with -1 side chain charge, plus charged N- and C- terminus, and the peptide backbone
  2. What amino acid would be the best candidate for heavy-atom derivatization?
    Cys (think of the sulfur; "heavy atom")
  3. A protein coated with SDS is both saturated with negative charge and has a configuration that is different than the native protein. [T/F]
  4. If there's a 1/100 dilution in a Beer's law problem, what should you do?
    Multiply the abs times 100 and multiply -all- the values together. Units of mM
  5. Which of the following can covalently modify a cystein residue?
    iodoacetic acid
  6. Chymotrypsin cleaves protein on the C-terminal side of this amino acid.
  7. Trypsin cleaves protein on the C-terminal side of this amino acid
  8. The side chain of this amino acid has a +1 charge at pH 7.0.
  9. This amino acid is always N-terminal in prokaryotic cells
  10. Ion-exchange chromatography can be used to reduce the number of purification steps due to its high specificity (affinity) for only the target protein. [T/F]
  11. Most proteins contain an approximately equal number of each of the 20 standard amino acids.
  12. According to classification by shape and solubility, to what class does collagen belong?
  13. What purification technique will separate particles on the basis of molecular size?
    size-exclusion chromatography
  14. What two amino acids contribute the most to the absorption of light at 280nm? Circle the one with the higher extinction coefficient.
    • Tryptophan (circled)
    • Tyrosine
  15. Approx. what vol of a protein is not occupied by protein atoms?
  16. Phenylisothiocyanate is a reagent that can be used for what two purposes when analyzing primary structure?
    • Edman degredation
    • N-terminal identification
  17. The two high-energy phosphate compounds that are primarily used to drive endergonic processes in living systems are ATP and GTP. [T/F]
  18. Which two amino acids are prevalent in B-turns?
    Proline and glycine
  19. In a volumetric flask...... find pH.
    • solve mol of both solutions
    • subtract them
    • put into a Hend-Hass equation with (base mol/diff mol) as the quotient
  20. A lock and a key is thought to be an accurate description.... [T/F]
  21. In EDI-MS of intact protein two adjacent m/z values in the mass spectrum can be used to determine a protein's molecular weight. [T/F]
  22. Which is true about naturally occuring monosacc?
    • D predominate
    • D,L do not specify light
  23. The B(1,4) glycosidic bond links the monomers in what macromolecule?
  24. Glycogen is similar to Amlyopectin but is more highly branched. [T/F]
  25. A phosphorylase enzyme releases carbohydrate on the __ end of starch and glycogen.
  26. To which amino acid are N-linked sacc attached?
  27. Triglycerides are composed of ___ mole of glycerol to ___ moles of fatty acids.
  28. Which of the following is not part of a polar head group in a glycerophospholipid?
  29. Terpenes are a class of lipids formed from combinations of ____ units.
  30. What is the primary function of a regulatory kinase?
    To phosphorylate a protein, either activating or deactivating it.
  31. When a molecule moves across a membrane from a concentration of 10-4 to 10-2, which of the following is true?
    An input of energy was required
  32. Which would be a good example of a receptor in a cell membrane that functioned to activate G-proteins.
    integral protein
  33. Membranes are asymmetric, heterogenous, dynamic structures at 37 degrees C.
  34. The biological role of restriction enzymes in bacteria is to...
    cleave foreign DNA
  35. DNA is resistant to alkaline hydrolysis due to the presence of a hydroxyl group in the 2' position. [T/F]
  36. Which of the following is correct concerning tRNA?
    tRNA is always composed of less than 100 nucleotide residues
  37. Ribosomes are composed of what two macromolecules?
    rRNA and Protein
  38. What kind of reaction does the following illustrate?
    double displacement kinetics
  39. When the pH of a solution is equal to the pKa of a weak acid...
    • you have a buffered solution
    • the conjugate base = weak acid
  40. Nucleic acids are linear polymers of nucleotides linked 3' to 5' by phosphodisester bonds. [T/F]
  41. What is the common name of the following pyrimidine base?
  42. What is the name of the following molecule?
  43. In this type of inhibition, the inhibitor can only bind to the ES complex to form an ESI complex.
  44. How does the binding of glucose to hexokinase influence activity?
    It induces a conforrmational change that forms the catalytic site
  45. The energy barrier between ES and the transition state must be as low as possible for effective catalysis, thus Km cannot be too ____.
  46. What are the three residues that form the catalytic triad of serine proteases?
    • His-57
    • Asp-102
    • Ser-102
  47. What reaction does pi-chymotrypsin catalyze?
    It cleaves itself to produce active chymotrypsin.
  48. What is the mutation that causes the molecular disease sickle-cell anemia?
    Glutamic acid (Glu) at position 6 of the B-chains are replaced with hydrophobic Valine
  49. What is the most prominent form of covalent modification where regulation is concerned?
    Reversible phosphorylation
  50. ATP and Glucose-6-Phosphate allosterically inhibit what enzyme involved in the release of stored carbohydrate?
    Glycogen phosphorylase
  51. What is the name and one primary function of the following molecule?
    cAMP; most common second messenger
  52. Which of the following has a sigmoidal shaped oxygen binding curve?
  53. What is the sigmoidal shape of the oxygen binding curve indicative of?
    Positive cooperativity in binding subsequent oxygen molecules
  54. Slope should ___ as more (and possibly even more) inhibitor is added to a lineweaver-burk plot?
    increase; get steeper
  55. Which of the following is found in connective tissue, cartilage, and bone?
  56. A peptide bond has about 75% double bond character, which leads to a planar structure. [T/F]
  57. Proteins tend to be ____ at their isoelectric points.
    • neutrally charged
    • least soluble
  58. What can be used to denature a protein?
    • HCL
    • Urea
    • pH
  59. How do you do a Keq equation?
    e to the (delta G*temp in K*1000)
  60. In gel-filtration chromatography, the higher the ____, the more efficient the separation of their components.
    column length
  61. ATP contains 2 pyrophosphate linkages. The hydrolysis of phosphoric acid anhydrides is highly favorable. [T/F]
  62. In eukaryotes....
    Introns and exons
  63. The ____ is a three base sequence in tRNA that H-bonds to the codon in mRNA during translation.