Silk is a natural polymer that humans have used for centuries to fabricate articles of clothing. By chemical composition, the polymer represents a fibrous protein. It is composed of smaller units called amino acids. In living organisms like silkworm, about 20 amino acids are added in a second. Hence, protein synthesis is said to be fast when compared with that of other macromolecules.
Simple organic molecules are produced from the elements such as carbon, oxygen, hydrogen, nitrogen that are present in Earth’s atmosphere under the influence of ultraviolet radiations of the Sun and other energy sources. When these small organic molecules are joined by biological medium, a "giant" molecule known as macromolecule is produced.
Macromolecules are polymers(in the Greek, polys means-many and meris-part). For example: A large molecule of protein consists of many small "units" linked together by covalent bonds. The repeated units of a polymer are called monomers. These serve as the building blocks.
Silk is a fibrous protein and has the α–helix formation over most of its length. In an α–helix, the peptide chain coils and their turns are held together by hydrogen bonds. In contrast to this, another type, β structure is possible in which the protein chains are stretched out as a folded sheet. The secondary structure arises due to the regular folding of the backbone of the polypeptide chain due to intramolecular hydrogen bonding between the carboxyl and amino groups.
Synthesis of protein is one fundamental biological processes by which individual cells build their specific proteins. The process takes place in multiple ribosomes simultaneously and all throughout the cell cytoplasm. A living cell can synthesize hundreds of different proteins every single second.