Which among the following is a constituent of natural silk?

The correct answer is Nitrogen.

Key Points

• Fibroin is the main component of silk fibres.
• It is a protein that cannot be dissolved. Sericin and fibroin are two major proteins found in protein raw materials.
• It contains the following amino acid sequence: (Gly-Ser-Gly-Ala-Gly-Ala)n. It is produced by silkworm caterpillar larvae but acquired from the cocoon.
• All of the constituents of silk, glycine, serine, and alanine include nitrogen. Serine's chemical formula is C₃H₇NO₃ glycine is NH₂‐CH₂‐COOH, and alanine is C3H7NO2.
• Potassium is not present as the constituent of fibroin and sericin proteins. Hence this is an incorrect option.
• Magnesium is not present in the chemical formula of amino acids present in fibroin and sericin proteins. Therefore, this is an incorrect option.
• The amino acids of the fibroin do not have a Phosphorus element. Hence this is an incorrect option.

Additional Information

•  The silk is produced by the larvae of the silkworm, but the silk fiber is obtained from the cocoon of the larvae.
• Sericulture is the science of the farming of silkworms for the commercial production of silk fiber.
• The most commonly used silkworm for this process is Bombyx mori. Silk is a continuous thread of a usual length of about 500 to 900 meters in each cocoon.