Spiders make their webs from lots of different
spider silk proteins. Some of them are
called 'spidroins' - Spidroin 1 and
Spidroin 2 and maybe some other spidroins.
They're in dragline silk, which is the
silk that spiders dangle from and is also almost
the same as the silk spokes in a spider's orb web.
The capture-silk spiral in the orb web is much
stretchier and not as strong as the dragline
silk. My students and I did experiments with
stretching silk and silk molecules, and a
scientist working with me said our results looked
like capture silk was a network of springs.
Dragline silk molecules pull apart
piece-by-piece, sort of like pulling open a row of
snaps. My student Emin discovered that by pulling
on the molecules with an atomic force microscope
Here's what I found by googling 'spider silk
chemicals' - "The protein in dragline silk is
fibroin (Mr 200,000-300,000) which is a
combination of the proteins spidroin 1 and
spidroin 2. The exact composition of these
proteins depends on factors including species and
diet. Fibroin consists of approximately 42%
glycine and 25% alanine as the major amino
Another article says spider silk is as strong
as steel and as stretchy as rubber and tougher
than Kevlar, but of course it's VERY thin.
I just read 2 news stories about spider silk.
One says the spider's silk proteins are stored as
blobs all packed together in its silk
gland, and when the silk blobs squeeze out of
the little hole in the silk gland, the squished
blobs all get long, to make a strand of silk. The
other news story says the silk spiral in the orb
web gets stiffer and stiffer, out toward the edges
of the spiral.
I like spiders and spider webs.
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