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Chapter 3 Intro,3.1,3.2

Chapter 3 Intro,3.1,3.2. Spider Webs and Carbon. Orb-Weaving Spider Web. Contains carbon. Polymer Science U. of A. Orb Spider Web. Spiders secrete their silk from glands located on their lower side.

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Chapter 3 Intro,3.1,3.2

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  1. Chapter 3Intro,3.1,3.2 Spider Webs and Carbon

  2. Orb-Weaving Spider Web • Contains carbon

  3. Polymer Science U. of A.

  4. Orb Spider Web

  5. Spiders secrete their silk from glands located on their lower side

  6. Silk being secreted from glands in the spigots • (SEM x3,740)

  7. Spinnerets

  8. Web Design

  9. Straight Strands • Radial • Dry • Inelastic proteins

  10. Radial Strands • “Spiraling strand”-captures insects • Wet • Sticky • Highly elastic (stretch up to 4X’s)

  11. The web is started with a horizontal thread stretchedbetween two supports. The spider lets out a thread that is carried to another support by a breeze or air current. The spider then pulls in the excess to stretch the thread taut.

  12. Dragline being silked from spinnerets

  13. The spider then moves to the center of the sagging, loose thread, and drops, letting out another thread and forming a ‘Y’.

  14. When the spider reaches the anchor point, it walks down the support to affix the new thread to another support point. The spider will spin threads between anchor points to give the web a frame.

  15. The spider makes the non-sticky scaffolding, from the outer edge to the center, attaching sticky threads that form the trap.

  16. The spider cuts away the non-sticky scaffolding as it progresses toward the center. The whole process of • building a web takes about a half hour.

  17. Web Design

  18. largest spigot produces the spider's safety line, called the dragline. • The smaller spigots produce lots of short sticky threads that make a strong attachment point for other silk lines.

  19. Coils..then straightens • Normal –Stretched5X- Stretched 20X

  20. Spider web glue droplets • SEM • on a strand of spider silk

  21. Why is there so little sag? • Coiling and uncoiling of silk fibers • When the prey is no longer pressing against the strand…the fluid’s surface tension “beads” and rewinds the fiber

  22. The spider uses its rear legs to pull and stretch the coagulated silk from the spinnerets

  23. What is Web Silk Made Of? • the primary constituents of spider silk turn out to be the two simplest amino acids, glycine and alanine

  24. "Dragline spider silk is actually stronger than Kevlar synthetic fiber- and Kevlar is several times stronger than steel"

  25. Spider Silk • Dragline silk • at least5X’s stronger than steel, • 2X’s more elastic than nylon waterproof and stretchable.

  26. Why don't spiders stick to their webs? Only a tiny area of its body in contact with the silk lines (the tips of its legs) + has a secretory lubrication on the claws • Why don't spiders stick to their webs? • Silk line with middle claw and bristles.

  27. Spider Silk Research • January 2002 spliced DNA from spiders into cells taken from hamsters and cows • These cells produced spider silk proteins

  28. Make Artificial Silk for: • Artificial tendons and ligaments • Surgical sutures • Bulletproof vests • Space Station Coatings • Fishing line

  29. USES -wear-resistant shoes and clothes -stronger ropes, nets, seatbelts, and parachutes -rust-free panels and bumpers for automobiles -improved sutures and bandages, artificial tendons and ligaments, and supports for weakened blood vessels. -soldiers and police long for bulletproof vests

  30. Organic Compounds • Contain carbon and synthesized by cells

  31. Carbon 6 p 6 n 6 e-

  32. Carbon can bond to 4 e- • Total of 6 electrons • 4e- in outer shell

  33. Can bond to 4 H

  34. Hydrocarbons • Contain hydrogen and carbon

  35. METHANE • One carbon

  36. Carbon Skeleton • Carbon Chain • Here with 6 carbons (hexane)

  37. Unbranched

  38. Can be branched • Like here with isooctane • (8 carbons)

  39. Rings • Cyclohexane

  40. Aspirin Note the ring

  41. Single bond (ethane) • Double bond (ethene) • Triple bond (ethyne)

  42. Isomers • Same molecular formula but different structure (orientation) • All C5H12

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