One of the meanings of the word fabric as given in dictionaries is ‘the underlying structure’. It shows how important fibers are to maintain life. We use phrases like “fabric of life”, “social fabric” etc. One of the most famous doctors of 16th century was Andreas Vesalius. He was a pioneer in dissecting directly the human dead bodies and not those of other animals, as was the custom then. His study including observations and sketches has been documented in his book “De Humani Corporis Fabrica”. The title of the book refers to the fabric i.e. structure of human body. Important fiberous proteins in animal bodies are - spongin fibers, collagen, keratin, chondrin, ossein, dentin, lamin, actin, myosin, elastin, reticulin, fibrin, fibroin, sericin, conchilin, lustrin.
Cells, which are the tiny units of live organisms, contain fibers. They secrete fibers and lay them in the matrix around which binds many cells together or helps hold the masses of cells together. Fibers thus make multicellularity possible. The first phylum of multicellular animals was the porifera, the phylum of sponges. The sponge body has several cells associated loosely. The substance cementing the cells contains fibers of a tough protein, spongin. Take a look at sponges http://library.thinkquest.org/26153/marine/porife.htm
As we come up in evolutionary ladder we get to know of a very wide range of many other proteins – the long molecules of proteins are like necklaces of amino acids, which are its repeating units. These units are comparable to the beads in a necklace. Some proteins are inside the cells, others out side the cells and some both inside and outside the cells. To name a few proteins which are involved in giving structural support – collagen, keratin, chondrin, ossein, dentin, lamin, actin, myosin, elastin, reticulin, fibrin, fibroin, sericin, conchilin, lustrin.
Let us just take a look at what these proteins achieve for the cells and organisms which secrete them.
Spongin forms a flexible network of fibers in which are lodged cells in a sponge. The spicules of Silica or Calcium or both, that make a skeleton stiff of sponge are deposited in the tangle of sponging fibers.
Collagen is a versatile protein with about a dozen types. The collagen is in skin, tendon,bones,cartilages, smooth muscles, ligaments, vitreous humor of eye and beneath all epithelial tissues. Collagen is the major structural protein of skin and it is responsible for tensile strength, elasticity, and pliability of the skin. It helps in resisting tension, allows expansion of an organ like blood vessel without collapsing, binding cells to connective tissue. It is no wonder that the collagen is a raw material for many major industries in leather, glue and cosmetics.
Written by Narayan Dattatray Wadadekar
Source: Suite101, October 21, 2005