Spider Silk

January 18, 2010
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What material is stronger than steel, ductile, and lightweight? You might say that kind of material does not exist. But there is a material that fits all of the above conditions. The correct answer is spider silk.

Spider silk, also known as gossamer, is so complex that scientists have tried to copy it for years. Spider silk is composed of many complex, protein molecules. There is also a repetitive nature of the DNA that encodes the silk protein. It is very difficult to determine the sequence.

Each spider specie has a different type of silk, which means that they all have a different protein sequence. However, there is generally a trend in the spider silk structure- a sequence of amino acids (glycine or alanine). “The beta sheets (3D structure of a protein) stack to from crystals, and the other parts form amorphous domains.” It is the reaction between the hard crystalline pieces and amorphous domains that gives spider silk its extraordinary properties. As hydrogen bonds in these areas break down, the silk obtains its toughness. Spiders also have an additional organ that helps them spin a special type of silk. It is called a cribellum. This organ is located in front of their spinnerets, which are a spider’s main silk-spinning organ.
Other compounds are also used in the making of spider silk. Pyrrolidine has hygroscopic properties and helps in keeping the silk moist. Potassium hydrogen phosphate will give off protons in aqueous solutions. This makes the silk acidic (ph 4) and protects it from fungi and bacteria that would otherwise break down the protein.

Humans have already found many useful places for silk. “Many people claim that spider silk facilitates the healing of wounds.” Books have shown us that many natives in the Asia have used spider silk to create nets for fishing and butterfly catching. It also can be used as a net. “During one period of time in our nation’s history, we even used spider silk as a thread for crosshairs in telescopes, microscopes and similar optical instruments.”

We often don’t think about the uses that spiders have for their own webs, besides using them to catch food. Obviously, different species have different purposes for their webs. However, there are three common uses. Spiders can use their silk as a safety net to catch them in case they fall. The next use they have is making a cocoon to live in. This creatively made “house” helps them to avoid predators and offers protection from the weather. The last use is for mating and reproduction uses. Females will spin a cocoon around their eggs, and males will spin a sperm web to allow them to change their pedipalps (an appendage near the mouth of a spider).
Our next major scientific breakthrough won’t be life on Mars or a way to prevent death. Instead, it will be something ordinary found on Earth. It will be spider silk.





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