Which among the following is a constituent of natural silk?

🔑 Key Points
🧵 Fibroin in Silk Fibres
→ Fibroin is the main component of silk fibres.
→ It is a protein that cannot be dissolved. Sericin and fibroin are the two major proteins found in raw silk.
→ The amino acid sequence in fibroin is: (Gly-Ser-Gly-Ala-Gly-Ala)n.
→ Fibroin is produced by silkworm larvae, acquired from the cocoon.
→ Glycine, serine, and alanine are the constituents of silk, all containing nitrogen.
→ Serine: C3H7NO3, glycine: NH₂-CH₂-COOH, and alanine: C3H7NO2.
→ Potassium is not present in the fibroin and sericin proteins, making it an incorrect option.
→ Magnesium is not present in the amino acids of fibroin and sericin, so it is also incorrect.
→ Phosphorus is absent in the amino acids of fibroin, making this option incorrect.

📝 Additional Information
→ Silk is produced by silkworm larvae, with the fiber obtained from the cocoon.
→ Sericulture is the science of farming silkworms for the commercial production of silk fiber.
→ The most commonly used silkworm is Bombyx mori.
→ The silk is a continuous thread, typically 500 to 900 meters in length per cocoon.