R
H2N C COOH
R
Where R= a radical, which is different for each of the known
amino acid.
Flow chart of silk filament extraction:
The caterpillar spins a cocoon from
two liquidsfibron(protein) and sericin(gum). It secrets them through a hole
called spinneret. This liquid sets in to silk fiber which the caterpillar winds
round itself.
Cocoon is harvested before the
caterpillar becomes a moth(approx. 10 days)
Cocoon is subjected to dry or wet heat
which kills the insects inside.Filaments ends are found and would on
to a reel. A single filament is too fine; therefore a number of cocoon are
would together, which results in raw silk or grease silk.
Reels are made up of a continuous
filament around 5000 meters long.
Several bundle are twisted together in
a throwing process which increase strength.