Chapter5

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Anonymous
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74565
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Chapter5
Updated:
2011-03-22 19:13:20
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Biology
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The Working Cell
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  1. cellular respiration
    chemical process that uses oxygen to convert the chemical energy stored in fuel molecules to a form of chemical energy that the cell can use to perform work
  2. ENDERgonic reactions
    "energy inward"
    yield products that are rich in potential energy
  3. metabolism
    • the total of an organisms chemical reactions.
    • intersecting metabolic pathways.
  4. metabolic pathway
    a series of chemical reactions that either builds a complex molecule or breaks down a complex molecule into simpler compounds
  5. energy coupling
    • the use of energy released from EXERgonic reactions to drive essential ENDERgonic reactions
    • a crucial ability of all cells
  6. ATP
    powers nearly all forms of cellular work
  7. phosphorylation
    • the transfer of a phosphate group, usually from ATP, to a molecule.
    • *nearly all cellular work depends on ATP energizing other molecules by phosphorylation
  8. Energy Activation (EA)
    the amount of energy that reactants must absorb before a chemical reaction will start
  9. enzymes
    proteins that function as biological catalysts, increasing the rate of a reaction without being consumed by the reaction
  10. substrate
    a specific reactant that an enzyme acts on
  11. active site
    the region of an enzyme that the substrate fits into
  12. induced fit
    the change in shape of the active enzyme, induced my entry of the substrate do that it binds more snuggly to the substrate
  13. competitive inhibitor
    • reduces an enzyme's productivety by blocking substrates from entering the active site
    • can be overcome by increasing the concentration of substrate
  14. fluid mosaic
    a description of a membrane structure, depicting a cellular membrane as a mosaic of diverse protein molecules embedded in a fluid bilayer made of phospholipid molecules
  15. selective permeability
    allow some substances to cross more easily than others
  16. concentration gradient
    • an increase/decrease in the density of a chemical substance in an area.
    • cells often maintain concentration gradients of ions across their membranes
    • when a gradient exists, substances tend to move from where they are more concentrated to where they are less concentrated
  17. passive transport
    the diffusion of a substance across a biological membrane, without any input of energy
  18. tonicity
    the ability of a solution surrounding the cell to cause that cell to gain or lose water
  19. isotonic solution
    has the same solute concentration as another solution, thus having no effect on passage of water into or out of the cell
  20. hypotonic solution
    • a solution with a concentration lower than that of the cell
    • the cell gains water, swells, and may burst
  21. hypertonic solution
    • a solution with a higher solute concentration
    • the cell shrivels and can die from water loss
  22. facilitated solution
    the passage of a substance through a specific transport protein across a biological membrane down its concentration gradient
  23. aquaporins
    a transport protein that very rapidly diffuses water into and out of cells
  24. active transport
    a cell must expend energy to move a solute against its concentration gradient-that is, across a membrane toward the side where the solute is more concentrated. the energy molecule ATP supplies most of the energy
  25. EXocytosis
    the movement of materials out of the cytoplasm of a cell by fusion of vesicles with the plasma membrane
  26. ENDocytosis
    cellular uptake of molecules or particles via formation of new vesicles from the plasma membrane
  27. PHAGocytosis
    cellular "eating"; a type of ENDocytosis where a cell engulfs macromolecules, other cells, or particles into its cytoplasm
  28. pinocytosis
    cellular "drinking"; a type of ENDocytosis in which the cell makes fluid and dissolved solutes into small membrane vesicles
  29. receptor-mediated endocytosis
    • the movements of specific molecules into a cell by the inward budding of membrane vesicles
    • the vesicles contain protein with receptor sites specific to the molecules taken in
  30. noncompetitive inhibitor
    • does not enter the active site, but instead binds to the enzyme somewhere else
    • its binding changes the shape of the enzyme so that the active site no longer fits the substrate
  31. feedback inhibition
    a method of metabolic control in which a product of a metabolic pathway acts as an inhibitor of an enzyme within that pathway
  32. energy
    the capacity to perform work
  33. kinetic energy
    • the energy of motion
    • transferring motion to other matter
  34. potential energy
    stored energy that an object possesses as a result of its location or structure
  35. chemical energy
    the potential energy available for release in a chemical reaction
  36. thermodynamics
    the study of energy transformation that occurs in a collection of matter
  37. First law of thermodynamics
    • the principle of the conservation of energy
    • energy can be transferred and transformed, but cannot be created or destroyed
  38. entropy
    • a measure of disorder or randomness
    • the more randomly arranged a collection of matter it, the greater its entropy
  39. Second law of thermodynamics
    • the principle whereby every energy conversion reduces the order of the universe, increasing its entropy
    • ordered forms of entropy are at least partly converted to heat
  40. EXERgonic reaction
    a chemical reaction that releases energy

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