Chem Lec - Ch.19

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Chem Lec - Ch.19
2010-03-26 22:36:21
Amino acids and Proteins

Amino acids and Proteins
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  1. Define: Acidic amino acid
    An amino acid that has an R group with a carboxylate (COO-) ion.
  2. What is a secondary level of protein structure, in which hydrogen bonds connect the N-H of one peptide bond with C=O of a peptide bond farther down the chain to form a coiled or corkscrew structure?
    alpha helix
  3. Define: alpha keratins
    Fibrous proteins containing mostly alpha helices found in hair, nails, and skin.
  4. What is the building block of proteins, consisting of an ammonium group, a carboxylate group, and a unique R group attached to the alpha carbon?
    Amino acids
  5. Define: Basic amino acid
    An amion acid that contains an R group with an ammonium (NH3+) ion.
  6. What is a secondary level of protein structure that consists of hydrogen bonds between peptide links in parallel polypeptide chains?
    beta-pleated sheet
  7. Define: C terminal
    The end amion acid in a peptide chain with a free carboxylate (COO-) group.
  8. What is the most abundant form of protein in the body, which is composed of fibrils of triple helics with hydrogen bonding between -OH groups of hydroproline and hydroxylysine?
  9. Define: denaturation
    the loss of secondary and tertiary protein structure caused by heat, acids, bases, organic compounds, heavy metals, and/or agitation.
  10. What is the covalent S-S bonds that form between the -SH groups of two cysteines in a protein to stabilize the tertiary struture?
    Disulfide bonds
  11. Define: electrophoresis
    the use of electrical current to separate proteins or other charged molecules with different isoelectric points
  12. What are amino acids that must be supplied by the diet because they are not synthesized by the body?
    essential amion acids
  13. Define: Fibrous proteins
    Proteins that are insoluble in water, consisting of polypeptide chains with alpha helices or beta-pleated sheets, and comprising the fibers of hair, wool, skin, nails, and silk.
  14. What are proteins that acquire a compact shapte from attractions between the R groups of the amino acids in the protein?
    Globular proteins
  15. Define: Hydrogen bonds
    the interactions between water and te polar R groups such as -OH, -NH2, and -COOH on the outside surface of a polypeptide chain.
  16. What is the attraction between polar R groups on the protein surface and water?
    Hydrophilic interactions
  17. Define: Hydrophobic interactions
    the attractions between nonpolar R groups on the inside of a globular protein
  18. What is the pH at which an amino acid exists as a zqitterion with a net charge of zero?
    isoelectric point (pI)
  19. Define: N terminal
    the end amino acid in a peptide with a free NH3+ group.
  20. What are amino acids with nonpolar R groups containing only C and H atoms?
    Nonpolar amino acids
  21. Define: peptide
    the combination of two or more amino acis joined by pepide bonds; dipeptide, tripeptide, and so on.
  22. What is the amide bond in peptides that joins the carboxylate group of one amion acid with the ammonium group in the next amino acid?
    peptide bonds
  23. Define:Polar amino acids (neutral)
    amino acids with polar R groups
  24. What is the specific sequence of the amino acids in protien?
    primary structure
  25. Define: Protein
    polypeptides containing many amino acids linked together by peptide bonds that are biologically active.
  26. What are protein structures in which two or more protin subunits form an active protein?
    Quaternary structure
  27. Define: Salt bridge
    the attraction between the ionized R groups of basic and acidic amion acids in the tertiary structure of a protein.
  28. Define: Secondary struture
    the formation of an alpha helix, beta-pleated sheet, or triple helix
  29. What is the folding of the secondary structure of a protein into a compact structure that is stabilized by the interactions of R groups such as ionic and disulfide bonds?
    tertiary struture
  30. Define: Triple Helix
    the protein structure found in collagen consisting of three polypeptide chains woven together like a braid
  31. What is the dipolar form of an amino acid consisting of two oppositely charged ionic regions, NH3+ and COO-?
  32. List each of the 7 classes of proteins and give its function in the body and an example of each.
    1) STRUCTURAL - provide structure; i.e. collagen & keratin, 2) CONTRACTILE - move muscles; i.e. myosin, 3) TRANSPORT - Carry essential substances through the body; i.e. Hemoglobin & Lipoproteins, 4) STORAGE - Store nutrients; i.e. casein, 5) HORMONE- body regulation; i.e. Insulin & Growth Hormone, 6) ENZYME - catalyze biochemical reactions; i.e. sucrase, 7)PROTECTION - destroy foreign bodies; i.e. Immunoglobulins
  33. What happens to H+ when pH < pI?
  34. What happens to H+ when pH > pI?