SILK

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EBLOCK :)
Ms Allen

Technical Name
Beta Keratin
Common Name
Silk
Structural Characteristics
Silk is made up of the amino acids GLY-SER-GLY-ALA-GLY and forms Beta pleated sheets. The main amino acid is GLY or glycine. The three amino acids bond into a long chain that is repeated and then the large amount of the acids for the Beta pleated sheets. This is the polymer that is known commonly as silk. Silk is a natural polymer and it is found in spyders and silkworms.
chemproj1.jpg

These three acids bond to create the polymer. When they are all connected they look like this:
chemproj2.jpg
This is a picture of how two amino acids bond to start the silk formation:
condensation_bonding.jpg

Physical and Chemical Characteristics
1. Triangular prism like structure
2. Triangular cross section with rounded corners
3. Lights hit it at many angles, allowing it to have a natural shine
4. Very strong but loses up to 20% of strength when wet
5. Smooth soft texture, but not slippery
6. Tension is due to covalent peptide bonds
7. Spider silk
a. Stretch up to 40% without breaking
b. Composed of protein molecules
c. Weaving spider silk properly could make it indestructible
Cross-Linking
Cross linking occurs with hydrogen bonds form with oxygen and hydrogen. Cross linking allows building up of these chains to bond together in big groups on the same plane. This results in the structures strength. The hydrogen that holds the helix together makes the silk have strength. Cross linking is the way that silk can be visable and durable .

MLA Citations
Kaplan, David L. "Silk Polymer Designs for Improved Expression and Processing." Defence Technical Information Ccenter 28 009 2007 http://stinet.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA473922.

Mathias, Jon L.. "Proteins and Polypeptides." NATURAL POLYMERS 2005 http://pslc.ws/mactest/natupoly.htm.

Brinkmann Instruments Inc, "Practical Information for the Molecular Biologist." Molecular Structure of the Amino Acids 2008 http://www.brinkmann.com/applications/practical-mole.asp.

"Silk." Wikipedia. 2008. Wikipedia. 16 May 2008 http://en.wikipedia.org/wiki/Silk#Chemical_properties.

"Show me the Molecules! ." Marvelous Molecules 2007 http://www.nyhallsci.org/marvelousmolecules/marveloussub.html.

http://www.itmonline.org/image/platy4.jpg
Becker, Nathan. " Molecular nanosprings in spider capture-silk threads ." Nature Materials 23 Mar 2003 http://www.nature.com/nmat/journal/v2/n4/fig_tab/nmat858_f1.html.

"Suture and prosthesis material." freepatentsonline 08/10/1982 <[[http://www.freepatentsonline.com/4343617.html%3E.%3C/span%3E%3C/span|http://www.freepatentsonline.com/4343617.html>.</span]]>