BI 253 Chapter 7

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medic11
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177316
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BI 253 Chapter 7
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2012-10-13 10:39:10
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BI 253
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Ch 7 10-11-12
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  1. What determines the shape of the cell? Cytomembrane or cytoskeleton?
    Cytoskeleton
  2. What are 2 general functions of cell membrane?
    • Forms boundaries between cells & molecular environments
    • Regulates mvmt of materials in & out of cell (selective permiability)
  3. What are 2 functions of the phospholipid bilayer?
    • Barrier for water-soluable molecules
    • Est physical integrity of the membrane
  4. What does cholesterol do in a phospholipid bilayer?
    Decreases Membrane Fluidity
  5. What are 3 structures that make up a membrane?
    • Primarily lipids (phospholipids & cholesterol)
    • Proteins
    • Carbohydrates
  6. What is the name of the model describing the basic structure of a cell membrane?
    Fluid Mosaic Model
  7. What factors can effect lateral mvmt of a cell?
    • Composition of fatty acids (saturated vs unsaturated)
    • High or low temp
  8. What is the effect of saturated & unsaturated fatty acids on fluidity?
    • Unsaturated & shorter inc fluidity
    • Saturated decrease fluidity
  9. What is a lipid raft & what effect does 1 have?
    • Portions of bilayer containing inc amts of cholesterol & saturated FA's
    • Decreased areas of fluidity in order to maintain position of a part of the cell
    • Leads to specialized functions
  10. If a protein is embedded into a bilayer it is called what?
    Integral membrane protein
  11. If a protein extends thru a bilayer & protrudes on both sides it is an integral membrane protein but more specifically a ___ ___.
    Transmembrane protein
  12. ___ ___ ___ are assoc but are not integrated w/other proteins & lipids in the bilayer.
    Peripheral membrane proteins
  13. With regards to H₂O, integral membrane proteins can be ___, ___ or ___.
    Hydrophilic, hydrophobic or both depending on where they interact w/the membrane
  14. Transmembrane proteins have 3 specific domains or areas within a membrane. They are?
    • Hydrophilic on outer side
    • Hydrophobic inside
    • Hydrophilic on inner side
  15. Peripheral membrane proteins lack ___ ___ b/c they are not ___ in the bilayer.
    • Hydrophobic regions
    • Embedded
  16. Peripheral membrane proteins have ___ or ___ R grps that interact w/integral membrane proteins or phospholipids giving 2 membrane surfaces ___ ___.
    • Polar or Charged
    • Different properties
  17. A membrane carb bound to a lipid is called a ____ & are used to ____ ___.
    • Glycolipid
    • Recognize a signal
  18. What are glycoproteins?
    Oligosaccharide chains covalently bonded to a protein
  19. Glycoproteins enable a cell to be what as well as allow for what?
    • Recognized by other cells
    • Cell to cell adhesion
  20. What are the 2 ways cells are able to arrange themselves into grps?
    • Cell Recognition
    • Cell Adhesion
  21. When 1 cell specifically binds to another cell of a certain type it is called ___ ___.
    Cell Recognition
  22. When the relationship between 2 cells is "cemented" it is called ___ ___.
    Cell Adhesion
  23. What 2 structures allow cells to recognize each other.
    • Glycolipids
    • Glycoproteins
  24. What are the 3 main categories of junctions?
    • Tight Junctions
    • Desmosomes
    • Gap Junctions
  25. Cellular adhesions form ___.
    Tissues
  26. Describe tight junctions.
    Specialized structures that link adjacent cells @ plasma membrane & seal tissues
  27. Tight junctions seal space between cells & provide the opportunity to what?
    Regulate what passes thru & direction of mvmt
  28. Tight junctions restrict migration of ___ ___ & ____ fr 1 region of cell to another.
    Membrane Proteins & phospholipids
  29. Desmosomes connect adjacent plasma membranes & create ___ ___.
    Mechanical Stability
  30. Describe structure of desmosomes.
    • Dense plaques on cytoplasmic surface of plasma membranes
    • Plaques attached to cytoplasmic fibers & membrane cell adhesion proteins
  31. Gap junctions facilitate ___-___ ___ between cells.
    Cell-Cell communication
  32. Describe a connexon.
    • Pore connected to a channel between 2 cells
    • Can be open or closed
    • Allows passage of ions, amino acids or nucleotides but NOT lg polymers
  33. What are the 2 kinds of transport?
    • Passive
    • Active
  34. What is the primary difference between passive & active transport?
    Passive requires NO energy while Active requires energy
  35. What is simple diffusion?
    Mvmt of molecules thru a phospholipid bilayer
  36. Describe facilitated diffusion.
    Mvmt of molecules thru use of membrane channel & carrier proteins
  37. What are the 2 types of passive transport?
    • Simple diffusion
    • Facilitated diffusion
  38. What is the definition of diffusion?
    Process of random mvmt toward a state of equilibrium
  39. What is the definition of equilibrium?
    Net mvmt of molecules fr regions of greater concen to regions of lesser concen until they equal out
  40. What are the 4 factors that speed of diffusion depend on?
    • Size of molecules or ions
    • Temperature
    • Electrical charge
    • Concentration gradient
  41. What effect does size of molecules or ions have on diffusion?
    Smaller size = faster diffusion
  42. How does temp effect diffusion?
    Higher temp = faster diffusion
  43. What does effect does elec charge have on diffusion?
    Law of electroneutrality - prevention of imbalance of ionic charge
  44. What effect does concentration gradient have on diffusion?
    Greater concentration gradient = faster diffusion
  45. Diffusion across membranes follow same principles as solutions IF . . . .
    The membrane is permeable to the substance
  46. What does a free card look like?
    This one
  47. Describe simple diffusion.
    Mvmt across a membrane that requires no energy
  48. What molecules do not pass readily across the lipid bilayer?
    Polar or Charged Molecules
  49. What do molecules do when moving along a membrane that is permeable to those molecules?
    Cross the membrane along a concentration gradient
  50. What do molecules do when moving along a membrane that is impermeable to those molecules?
    Remains on 1 side or the other
  51. The hydrophobic interior of plasma membrane tends to exclude hydrophilic substances. . .T or F
    True
  52. What is osmosis?
    Simple diffusion of water across a membranes
  53. Always remember WATER FOLLOWS ____.
    • Solute
    • ie strawberries & sugar
  54. Where is solute greater in hypertonic solution & where will water go w/regards to a cell?
    • Outside the cell
    • Fluid will go OUT of cell
  55. Where is solute greater in hypotonic solution & where will water go w/regards to a cell?
    • Inside cell
    • Outside solvent will flow into cell
  56. In an isotonic solution, solutes are ___ ___ & ___ of a cell.
    Equal inside & out
  57. Polar & charged substances (do or do not) diffuse across lipid bilayers?
    Do NOT
  58. What is facilitated diffusion?
    Passive process, ctrled by concentration gradients utilizing special membrane proteins to allow polar or charged substances across a lipid bilayer
  59. How much energy is needed for facilitated diffusion?
    NONE
  60. What are the 2 types of facilitated diffusion?
    • Channel protein aided
    • Carrier protein aided
  61. What are 3 characteristics of structure of channel proteins?
    • Transmembrane
    • Lined w/polar amino acids
    • Nonpolar (hydrophobic) amino acids face toward fatty acid tails of lipid molecules
  62. Gated channel proteins open when . . .
    Something changes 3-D shape of its protein
  63. What are 2 types of gated channels?
    • Ligand-gated channel
    • Voltage gated channel
  64. What is a ligand?
    Special molecule that binds to a receptor & causes a response
  65. Once a channel protein is open ions can rush ___ or ___ usually depending on what factors?
    • In or out
    • Concentration gradient &/or Electromechanical gradient
  66. How do carrier proteins function?
    Protein changes shape to "carry" molecule thru membrane
  67. Active transport is mvmt of ions or molecules ___ concentration gradient w/addition of ___.
    • Against
    • Energy
  68. What are the 3 active transport systems?
    • Uniport
    • Symport
    • Antiport
  69. A uniport transporter moves. . . .
    1 substance 1 direction
  70. A symport transporter moves __ ___ the ___ ___.
    • 2 solutes
    • Same direction
  71. Symport transporters are AKA?
    Coupled transport
  72. Antiport transporters move ___ ___ in ___ ___.
    • 2 solutes
    • Opposite directions
  73. What are the 2 types of active transport?
    • Primary Active Transport
    • Secondary Active Transport
  74. What differentiates the 2 types of active transport?
    Primary uses ATP directly & Secondary uses ATP indirectly
  75. Only ___ are transported by pumps that utilize a primary active transport system
    • Cations
    • ie Sodium potassium exchange pump
  76. Explain how secondary active transport works.
    • ATP consumed to create an ion gradient
    • Gradient then used to move substance
  77. Endocytosis is bringing molecules ___ the cell.
    Into
  78. Exocytosis is bringing molecules ___ the cell.
    Out of
  79. Why can't Proteins, polysaccharides & nucleic acids pass thru membranes?
    Too large & too charged
  80. What are 3 main types of endocytosis?
    • Phagocytosis
    • Pinocytosis
    • Receptor-Mediated Endocyosis
  81. What is the process by which white blood cells eat bacteria?
    Phagocytosis
  82. Which form of endocytosis is for transport of SPECIFIC molecules?
    Receptor Mediated endocytosis
  83. What are steps in process of endocytosis?
    • Plasma membrane surrounds a molecule forming vacuole or vesicle
    • Vacuole or vesicle breaks off & moves to its destination
  84. Phagocytic vesicles are called ___.
    Phagosomes
  85. Phagocytosis is . . . .
    Non-specific cell eating where lg particles are ingested
  86. The process of cell drinking of non-specific dissolved substances & fluids is called ____.
    Pinocytosis
  87. Specialized integral membrane proteins act as receptors in what form of endocytosis?
    Receptor-mediated endocytosis
  88. A protein that binds to a specific molecule & initiates a biological response is called a ____.
    Receptor
  89. What is a specific molecule that binds to a receptor called?
    Ligand
  90. When a ligand binds to a receptor what 3 things could happen?
    • Cellular changes
    • Genes - on or off
    • Assist in transport
  91. In receptor mediated endocytosis, a forming vesicle is called a ___ ___.
    Coated pit
  92. A coated pit & a coated vesicle are covered with what?
    Coat protein called clathrin
  93. ___ break macromolecules down into their components.
    Lysosomes

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