bio 121 test 2

  1. integral
    -firmly bound to membrane
    -transmembrane proteins span the membrane
    -bound to integral proteins
    **function in transport, enzymes, and receptors
    Membrane Proteins
  2. membranes are readily permeable to:
    • lipid-soluble molecules
    • water
    • gases (oxygen, carbon dioxide)
  3. membranes are semi-____________
  4. movement of atoms due to vibrational energy
    -all atoms above 0 degrees kelvin move (very cold)
    -follows a concentration gradient > high to low

    kidney dialysis relies on diffusion, removes wastes from blood
  5. -special case of diffusion
    -movement of water across a semi-permeable membrane
    -follows concentration gradient
    -influenced by solute concentration and pressure
  6. solvent + solute =
  7. water _________ is a function of solute and pressure (if in a container)
    -solute will cause water to move
    -pressure can overcome influence of solute
  8. water movement... terms that are applied to solutions and their effects on cells (outside relative to inside)
    • isotonic solutions
    • hypertonic solutions
    • hypotonic solutions
  9. same as inside, no effect
    isotonic solution
  10. crenate, plasmolyze
    hypertonic solutions
  11. lysis, turgidity
    hypotonic solution
  12. small molecules move across the plasma membrane in _______ directions
  13. substances do not move indiscriminately, membranes are ___________ ___________
    selectively permeable
  14. __________ depends on the interaction of a molecule with the hydrophobic core of the membrane
    -hydrophobic molecules, like hydrocarbons CO2 and O2 can cross easily
    -ions and polar molecules pass through with difficulty
    -proteins can assist and regulate the transport of ions and polar molecules
  15. many polar molecules and ions that are normally impeded by the lipid bilayer of the membrane diffuse passively with the help of ________ ________ that span the membrane.
    transport proteins
  16. the passive movement of molecules down its concentration gradient via a transport protein is called __________ __________
    facilitated diffusion
  17. many transport proteins simply provide corridors allowing a specific molecule or ion to cross the membrane. these _______ _______ allow fast transport
    ex) water _______ _______, aquaprorins, facilitate massive amounts of diffusion
    channel proteins
  18. some channel proteins, _______ _______, open or close depending on the presence or absence of a physical or chemical substance
    gated channels
  19. _______ _______ is the pumping of solutes against their gradients
    -requires the cell to expand its own metabolic energy
    -critical for a cell to maintain its internal concentrations of small molecules that would otherwise diffuse across the membrane
    active transport
  20. some facilitated transport proteins can move solutes against their concentration gradient, from the side where they are _______ concentrated to the side where they are _______ concentrated
    less, more
  21. -active transport is performed by specific proteins embedded in the membranes
    -_______ supplies the energy for most active transport
    -often _______ powers active transport by shifting a phosphate group from _______ (forming ADP) to the transport protein > may induce conformational change in transport protein that translocates the solute across the membrane
  22. the _______-_______ _______ actively maintains the gradient of sodium and potassium ions across the membrane
    -typically, animal cells have higher K+ and lower Na+ concentrations inside cell
    -_______-_______ _______ uses energy of one ATP to pump three Na+ ions out and two K+ ions in
    sodium-potassium pump
  23. a single ATP-powered pump that transports one solute can indirectly drive the active transport of several other solutes through _______ via a different protein
  24. plants commonly use the gradient of hydrogen ions that is generated by proton pumps to drive the active transport of amino acids, sugars, and other nutrients into the cell
    the high concentration of H+ on one side of the membrane, created by the proton pump, leads to the facilitated diffusion of protons back, but only if another molecule, like sucrose, travels with the hydrogen ion
  25. -small molecules and water enter or leave the cell through the lipid bilayer or by transport proteins
    -large molecules, such as polysaccharides and proteins, cross the membrane via vesicles
    -during _______, a transport vesicle budded from the Golgi apparatus is moved by the cytoskeleton to the plasma membrane
    -when the two membranes come in contact, the bilayers fuse and spill the contents to the outside
  26. during _______, a cell brings in macromolecules and particulate matter by forming new vesicles from the plasma membrane
    -a small area of the plasma membrane sinks inward to form a pocket
    -as the pocket into the plasma membrane deepens, it pinches in, forming a vesicle containing the material that had been outside the cell
  27. one type of endocytosis is _______, "cellular eating"
    -cell engulfs a particle by extending pseudopodia around it and packaging it in a large vacuole
    -the contents of the vacuole are digested when the vacuole fuses with a lysosome
  28. in _______, "cellular drinking," a cell created a vesicle around a droplet of extracellular fluid
    -this is a non-specific process
  29. _______-_______ _______ is very specific in what substances are being transported
    receptor-mediated endocytosis
  30. receptor-mediated endocytosis is triggered when extracellular substances bind to special receptors, _______, on the membrane surface, especially near coated pits
    -this triggers the formation of a vesicle
  31. cells receive different types of signals
    • chemical
    • electromagnetic
    • mechanical
  32. -cell signaling evolved early
    -mating types in saccharomyces cerevisiae
    -there are two sexes, ________ and ________, each of which secretes a specific signaling molecule, ________ factor and ________ factor respectively-these factors each bind to receptor proteins on the other mating type
    a, alpha
  33. communicating cells may be close together or far apart > ________ ________ that influence cells in the local vicinity
    local regulators
  34. ________ signal at greater distances
    -in animals, ________ travel through the circulatory system to target cells in other parts of the body
    -in plants, ________ travel in vessels, move from cell to cell or diffuse in air
    -cells may communicate by direct contact
  35. three stages of signal transduction
    • reception
    • transduction
    • response
  36. chemical signal binds to a cellular protein, typically at the cell's surface
  37. -binding causes a change in the receptor
    -triggers changes along a signal-transduction pathway
  38. the transduced signal triggers a specific cellular activity
  39. a ________ ________ binds to a receptor protein causing the protein to change shape
    -target cell has a receptor protein that recognizes the ________ ________
    -a ligand attaches to the receptor protein, the receptor changes shape
    signal molecule
  40. most signal receptors are ________ ________ proteins
    -most signal molecules are water-soluble and too large to pass through the plasma membrane
    plasma membrane
  41. three major types of receptors
    • g-protein-linked receptors
    • tyrosine-kinase receptors
    • ion-channel receptors
  42. a ________-________-________ receptor consists of a receptor protein associated with a G-protein on the cytoplasmic side
    -effective signal molecules include yeast mating factors, epinephrine, other hormones, and neurotransmitters
  43. the g-protein acts as an ________-________ switch
    on, off
  44. if GDP is bound, the G protein is ________
    if GTP is bound, the G protein is ________
    inactive, active
  45. -when a g-protein-linked receptor is activated by binding with an extracellular signal molecule, the receptor binds to an inactive g protein in membrane
    -this leads the g-protein to substitute ________ for ________
    -the g-protein then binds with another membrane protein, often an enzyme, altering its activity and leading to a cellular response
    GTP, GDP
  46. -the g-protein can also act as a GTPase enzyme and ________ the GTP, which activated it to GDP
    -this change turns the G protein off
    -the whole system can be shut down quickly when the extracellular signal molecule is no longer present
  47. in addition to functions already mentioned, g-protein receptor systems play an important role during ________ ________ and sensory systems
    embryonic development
  48. -the ________-________ receptor system is especially effective when the cell needs to regulate and coordinate a variety of activities and trigger several signal pathways at once
    -extracellular growth factors often bind to ________-________ receptors
    -the cytoplasmic side of these receptors function as a ________-________, transferring a phosphate group from ATP to tyrosine on a substrate protein
  49. -an extracellular signal-binding site
    -a single alpha helix spanning the membrane
    -an intracellular tail with several tyrosines
    parts of tyrosine-kinase receptors
  50. when ligands bind to two receptors polypeptides, the polypeptide aggregates, forming a ________
    -this activates the tyrosine-kinase section of both
    -these add phosphates to the tyrosine tails of the other polypeptide
  51. the fully activate receptor proteins activate a variety of specific relay proteins that bind to specific ________ tyrosine molecules
  52. one tyrosine-kinase receptor dimer may activate ________ or more different intracellular proteins simultaneously
  53. activated relay proteins trigger many different ________ pathways and responses
  54. protein pores that open or close in response to a chemical signal
    -allows or blocks ion flow
    -binding by a ligand to the extracellular side changed the protein's shape and opens the channel
    -ion flow changed the concentration inside the cell
    -when the ligand dissociates, the channel closes
    -very important in nervous system
    ligand-gated ion channels
  55. other signal receptors are dissolved in the ________ or nucleus of target cells
    -the signals pass through the plasma membrane
    -these chemical messengers include the hydrophobic steroid and thyroid hormones of animals
    -also in this group is nitric oxide, a gas whose small size allows it to slide between membrane phospholipids
  56. ________, like other hormones, travels through the blood and enters cells throughout the body
    -in the cytosol, the bind and activate receptor proteins
    -these activated proteins enter the nucleus and turn on genes that control male sex characteristics
  57. control which genes are turned on (which genes are transcribed into messenger RNA)
    -the mRNA molecules leave the nucleus and carry information that directs the synthesis (translation) of specific proteins at the ribosome
    -other intracellular receptors re already in the nucleus and bind to the signal molecules there
    transcription factors
  58. the totality of an organism's chemical reactions
  59. metabolic pathway are a series of chemical reactions controlled by ________
    -whole thing depends on presence/function of these
  60. release energy by breaking down complex molecules to simpler molecules
  61. consume energy to build complicated molecules from simpler compounds
  62. capacity to do work, to move matter against opposing forces
  63. energy of motion
  64. energy that matter possesses because of its location or structure
  65. form of potential energy in molecules because of arrangement of nuclei and electrons in their atoms
    chemical energy
  66. a central property of all living organisms is to ________ ________
    transport energy
  67. the study of energy transformations
  68. energy can be transferred or transformed, but not created or destroyed
    1st law of thermodynamics
  69. every energy transformation must make the universe more disordered
    2nd law of thermodynamics
  70. quantity used as a measure of disorder or randomness
  71. most of increased entropy of universe takes form of ________ heat. Heat is energy in its most random state
    ex: friction

  72. -provides criterion for measuring spontaneity of a system
    -portion of a system's energy that is able to perform work
    -organisms live at expense of this
    free energy
  73. ________ processes can occur without outside help
  74. ________ processes can only occur if energy is added to a system
  75. -net release of free energy
    -delta G is negative
    exergonic reaction
  76. -absorbs free energy from surroundings
    -store energy
    -delta G is positive
    -not spontaneous
    endergonic reaction
Card Set
bio 121 test 2
bio 121 test 2