CellBio4

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Anonymous
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104365
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CellBio4
Updated:
2011-09-26 03:14:16
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cell bio
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Chapter 4
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  1. Of the four classes of cellular macromolecules, which one is not a component of cell membranes?

    A. proteins
    B. lipids
    C. nucleic acids
    D. carbs
    Nucleic Acids
  2. How do membranes function as a locus of biochemical reactions?
    Membranes hold enzymes of sequential reaction in close proximity.
  3. Features of the fluid mosaic model of membrane structure include:
    A lipid bilayer, dynamic motion of both membrane lipids and proteins, and proteins that may either rest of the surface of penetrate the membrane.
  4. The relative proportion (by weight) of lipid and protein in a membrane:
    varies depending upin the source of the membrane
  5. Phosphoglycerides that are negativley charged include:
    phosphatidylinositol and phosphatidylserine.
  6. Membrane carbohydrates occur as:
    either glycoproteins or glycolipids, but are not free in the membrane
  7. A membrane-affiliated protein is isolated by detergent extraction, and found to be amphipathic and lacking any nonprotein components. To which class of membrane proteins does it belong?
    • integral proteins
  8. Site-directed cross-linking is a technique that gives insight into what property of integral membrane proteins?
    • proximity of various membrane-spanning domains to each other
  9. A neurotransmitter that binds to a postsynaptic cell and opens Na+ channels:
    Both excites the postsynaptic cell and depolarizes the postsynaptic cell.
  10. The portion of a membrane protein that passes through the lipid bilayer, often composed of non-polar amino acids in a a-helical conformation.
    Transmembrane Domain
  11. A class of membrane lipids -- derivations of sphingosine -- that consist of sphingosine linked to a fatty acid by its amino group.
    sphingolipids
  12. Property of one compartment having a higher solute concentration compared with that in a given compartment.
    Hypertonic ( or hyperosmotic )
  13. A membrane-associated protein that is located outside the bilayer but is covalently linked to a lipid molecule within the bilayer.
    Lipid-Anchored Protein
  14. Any molecule that can bind to a receptor beacuse it has a complementary structure.
    Ligand
  15. The movement of small ions across membranes is called ___
    conductance
  16. The point during depolarization of an excitable cell where voltage-gated sodium channels open, with the resulting Na+ influx causing a brief reversal in membrane potential.
    Threshold
  17. Property of one compartment having the same solute concetration compared with that in a given compartment.
    Isotonic
  18. The lipd rich material wrapped around most neurons in the vertebrate body.
    Myelin Sheath
  19. List the 7 key membrane functions byatch!
    • 1. Compartmentalize
    • 2. Scaffold for biochemical activities- organizes enzymes
    • 3. Selectively permeable barrier
    • 4. Transport solutes
    • 5. Respond to external signals
    • 6. Intracellular interaction
    • 7. Energy transduction
  20. Interesting Fact!!!
    Membranes are composed mostly of lipids. This was shown because their dissolving power matched that of oil.
  21. Ask yourself this question... "how do cells get things such as polar solutes and ions across their membrane?".... you know this!
    Protein lined pores in the membrane allow movement of polar solutes and ions across cell boundaries.
  22. The chemical composition of lipids vs. proteins (ratio wise) is what..
    the ratios vary among membrane types
  23. Lipid bilayers assemble spontaneously in aqueous solutions into ___
    Liposomes
  24. Carbohydrates covalently linked to lipids and proteins on the ____ surface of the bilayer.
    extracellular
  25. Glycoproteins have short, brancehd carbohydrates for interactions with other cells and structures outside the cell.
    cool
  26. _____ have larger carbohydrate chains that may be cell-to-cell recognition sites
    glycolipids
  27. Integral Proteins
  28. look up
  29. Peripheral Proteins
  30. look up... sorry
  31. Lipid-Anchored Proteins
  32. look up... sorry again
  33. Membrane carbohydrates occur as ....
    either glycoproteins or glycolipids, but are not free in the membrane

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