Chem Ch. 19

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Chem Ch. 19
2010-03-30 17:20:05
Amino Acids and Proteins

Amino acids ans proteins
Show Answers:

  1. What clas of protein would be in horns?
  2. What kinds of bonds occur in the primary structure of a protein?
    peptide bonds
  3. What are the partial charges of the H in N-H and the O in C=O that permits hydrogen bonds to form?
    peptide bonds
  4. How do the hydrogen bonds differ in a beta-pleated sheet from the alpha helix?
    In a a-helix, there are many hydrogen bonds along the polypeptide, it has the helical shape of a coiled telephone cord. In a b-pleated sheet, polypeptide chains are held together side by side by hydrogen bonds between the peptide chains.
  5. What are some of the amino acids in collagen that form hydrogen bonds between the polypeptide chains?
    glycine, proline, and alanine
  6. Would hydrophilic amino acids be found on the outside or inside of the myoglobin structure?
  7. Why does hair have a large amount of cysteine amino acids?
    In hair, 3 alpha helices coil together like a braid to form a fibril. Within the fibril, the alpha helices are held together by disulfide (s-s) linkages between the R groups of the many cysteine amino acids in hair. Several fibrils bind together to from a strand of hair.
  8. What is the difference between a tertiary structure and a quarternay structure?
    A tertiary structure is a single protein folded into a 3D shape, but a quaternary sturcture is 2 or more proteins combined to form a biologically active protein
  9. What is the difference between a primary structure and a tertiary structure?
    A primary structure is a sequence of amino acids, but a tertiary structure is a protein folded into a 3D shape stablilized by interactions between R groups of amino acids
  10. What are some ways in which proteins are denatured?
    heat, acids and bases, organic compounds, heavy metal ions, and agitation
  11. Define: Acidic amino acid
    An amino acid that has an R group with a carboxylate (-COO-) ion.
  12. What is a secondary level of protein of protein structure, in which hydrogen bonds connect the N-H of one peptide bond with the C=O of a peptide bond farther down the chain to form a coiled or corkscrew structure?
    Alpha helix
  13. Define: Alpha keratins
    Fibrous proteins containing mostly alpha helices found in hair, nails, and skin
  14. What are the building blocks of proteins, consisting of an ammonium group, a carboxylate group, and a unique R group attached to the alpha carbon?
    amino acids
  15. Define: Basic amino acid
    An amino acid that contains an R group with an ammonium (-NH3+) ion
  16. What are a secondary level of protein structure that consists of hydrogen bonds between peptide links in parallel polypeptide chains?
    Beta-pleated sheet
  17. Define: C Terminal
    The end amino acid in a peptide chain with a free carboxylate (-COO-) group
  18. What are the most abundent form of protein in the body, which is composed of fibrils of triple helices with hydrogen bonding between -OH groups of hydroxyproline and hydroxylysine?
  19. Define: Denaturation
    The loss of secondary and tertiary protein structure caused by heat, acids, bases, organic compounds, heavy metals, and/or agitation.
  20. What are covalent S-S bonds that form between the -SH groups of two cysteines in a protein to stablize the tertiary structure?
    disulfide bonds
  21. Define: Electrophoresis
    The use of electrical current to separte proteins or other charged molecules with different isoelectric points
  22. What are amino acids that must be supplied by the diet because they are not synthesized by the body?
    Essential amino acids
  23. Define: Fibrous proteins
    Proteins that are insoluble in water; consisting of polypeptide chains with alpha helices or beta-pleated sheets, and comprising the fibers fo hair, wool, skin, nails, and silk
  24. What are proteins that acquire a compact shcape from attractions between the R groups of the amino acids in the protein?
    Globular proteins
  25. Define: Hydrogen bonds
    the interactions between water and the polar R groups such as -OH, -NH2, and -COOH on the outside surface of a polypeptide chain
  26. What are the attractions between polar R groups on the protein surface and water?
    Hydrophilic interactions
  27. Define: Hydrophobic interactions
    The attractions between nonpolar R groups on the inside of a globular protein
  28. Define: Isoelectic point (pI)
    The pH at which an amino acid exists as a zwitterion with a net charge of zero
  29. What is the end amino acid in a peptide with a free -NH3+ group?
    N terminal
  30. Define: Nonpolar amino acids
    Amino acids with nonpolar R groups containing only C and H atoms
  31. Define: Peptide
    the combination of two or more amino acids joined by peptide bonds; dipeptide, tripeptide, and so on.
  32. What are the amide bonds in peptides that joins the carboxylate group of one amino acid with the ammonium group in the next amino acid?
    peptide bond
  33. Define: Polar amino acids (neutral)
    Amino acis with polar R groups
  34. What is the specific sequence of the amino acids in a protein called?
    Primary structure
  35. Define: Protein
    polypeptides containing many amino acids linked together by peptide bonds that are biologically active
  36. What is a protein structure in which two or more protein subunits form an active protein?
    Quarternary structure
  37. Define: Salt bridge
    the attraction between the inoized R groups of basic and acidic amino acids in the tertiary structure of a protein
  38. What is the formation of an alpha helix, beta-pleated sheet, or triple helix?
    secondary structure
  39. Define: Tertiary structure
    The folding of the secondary structure of a protein into a compact structure that is stablized by the interactios of R groups such as ionic and disulfide bonds
  40. What is the protein structure found in collagen consisting of three polypeptide chains woven together like a braid?
    Triple helix
  41. Define: Zwitterion
    The dipolar form of an amino acid consisting of two oppositely charged ionic regions, -NH3+ and -COO-