full transcript

From the Ted Talk by Rob Ulrich: How do oysters make pearls?

Unscramble the Blue Letters


Mollusks carefully control all components of their calcium carbonate creations— even manipulating CaCO3 at the mueaocllr lveel. Using special proteins, mollusks can produce two crystal suetctrrus out of CaCO3: catlcie and aragonite. Both of these compounds have the same chemical composition, but different qualities due to the way their crystal lattices are arranged.

Calcite is the more stable of the two and less porne to doissvlnig over time, so most mollusk shells have a sturdy outer layer of calcite. As the slightly more soluble molecule, aragonite can better adapt to more or less acidic environments. So most msoullk shells have an interior leayr of aragonite to maintain their internal pH level. But one form of aragonite is sgorentr and more versatile than the rest: nacre. Mollusks make this special material by placing successive layers of aragonite interspersed with proteins. These layers are stacked like heaaognxl bricks, each surrounded by other organic material that directs their orientation. The uniform layering and brick-like structure of nacre is key to its signature iridescence. The layers are similar in tikhcsens to the weglenatvh of vislbie light, so the light reflecting from its irtineor surface interferes with the light reflecting from the oteur surface. When particles of light strike the nacre, they bounce around its multilayered crystalline structure in a cascade of shnfitig rainbows.

Open Cloze


Mollusks carefully control all components of their calcium carbonate creations— even manipulating CaCO3 at the _________ _____. Using special proteins, mollusks can produce two crystal __________ out of CaCO3: _______ and aragonite. Both of these compounds have the same chemical composition, but different qualities due to the way their crystal lattices are arranged.

Calcite is the more stable of the two and less _____ to __________ over time, so most mollusk shells have a sturdy outer layer of calcite. As the slightly more soluble molecule, aragonite can better adapt to more or less acidic environments. So most _______ shells have an interior _____ of aragonite to maintain their internal pH level. But one form of aragonite is ________ and more versatile than the rest: nacre. Mollusks make this special material by placing successive layers of aragonite interspersed with proteins. These layers are stacked like _________ bricks, each surrounded by other organic material that directs their orientation. The uniform layering and brick-like structure of nacre is key to its signature iridescence. The layers are similar in _________ to the __________ of _______ light, so the light reflecting from its ________ surface interferes with the light reflecting from the _____ surface. When particles of light strike the nacre, they bounce around its multilayered crystalline structure in a cascade of ________ rainbows.

Solution


  1. molecular
  2. shifting
  3. layer
  4. interior
  5. outer
  6. structures
  7. visible
  8. mollusk
  9. calcite
  10. wavelength
  11. dissolving
  12. level
  13. stronger
  14. prone
  15. hexagonal
  16. thickness

Original Text


Mollusks carefully control all components of their calcium carbonate creations— even manipulating CaCO3 at the molecular level. Using special proteins, mollusks can produce two crystal structures out of CaCO3: calcite and aragonite. Both of these compounds have the same chemical composition, but different qualities due to the way their crystal lattices are arranged.

Calcite is the more stable of the two and less prone to dissolving over time, so most mollusk shells have a sturdy outer layer of calcite. As the slightly more soluble molecule, aragonite can better adapt to more or less acidic environments. So most mollusk shells have an interior layer of aragonite to maintain their internal pH level. But one form of aragonite is stronger and more versatile than the rest: nacre. Mollusks make this special material by placing successive layers of aragonite interspersed with proteins. These layers are stacked like hexagonal bricks, each surrounded by other organic material that directs their orientation. The uniform layering and brick-like structure of nacre is key to its signature iridescence. The layers are similar in thickness to the wavelength of visible light, so the light reflecting from its interior surface interferes with the light reflecting from the outer surface. When particles of light strike the nacre, they bounce around its multilayered crystalline structure in a cascade of shifting rainbows.

Frequently Occurring Word Combinations


ngrams of length 2

collocation frequency
calcium carbonate 3
carbon dioxide 2
mollusk species 2
mollusk shells 2
light reflecting 2


Important Words


  1. acidic
  2. adapt
  3. aragonite
  4. arranged
  5. bounce
  6. bricks
  7. calcite
  8. calcium
  9. carbonate
  10. carefully
  11. cascade
  12. chemical
  13. components
  14. composition
  15. compounds
  16. control
  17. crystal
  18. crystalline
  19. directs
  20. dissolving
  21. due
  22. environments
  23. form
  24. hexagonal
  25. interferes
  26. interior
  27. internal
  28. interspersed
  29. iridescence
  30. key
  31. lattices
  32. layer
  33. layering
  34. layers
  35. level
  36. light
  37. maintain
  38. manipulating
  39. material
  40. molecular
  41. molecule
  42. mollusk
  43. mollusks
  44. multilayered
  45. nacre
  46. organic
  47. orientation
  48. outer
  49. particles
  50. ph
  51. placing
  52. produce
  53. prone
  54. proteins
  55. qualities
  56. rainbows
  57. reflecting
  58. shells
  59. shifting
  60. signature
  61. similar
  62. slightly
  63. soluble
  64. special
  65. stable
  66. stacked
  67. strike
  68. stronger
  69. structure
  70. structures
  71. sturdy
  72. successive
  73. surface
  74. surrounded
  75. thickness
  76. time
  77. uniform
  78. versatile
  79. visible
  80. wavelength