Spider web

Untangling Spider webs

By Juman Hijab

Updated on: August 15, 2021 Original date: January 15, 2020

Golden silk spider web

 

Hydrogen bonds are living malleable glue. 

They help bring things together to create living systems. 

Natural Fibers and hydrogen bonds

Silk fibers

Natural fibers, like hair, silk, wool, and Abaca fibers* (shown in picture on right) have long strings of amino acids, with each molecule attached to the next – like a chain of paper clips.

These molecules connect through strong structural bonds.

Thicker strands form when those microscopic threads of amino acid chains connect to each other. Those threads connect with weak hydrogen bonds, looking very much like pliable railroad tracks.

Do other natural molecules also have hydrogen bonds?

Yes, basically. Look at any molecule that has been made for a “living” purpose; these molecules all have some element of hydrogen bonding bringing them together:

The bark in the tree, the DNA in our cells, the mucus that we cough up, the tears that we shed!

Hydrogen bonds are the living glue that links us, one molecule at a time.Hydrogen bonds

Living furniture glue

The easiest way to think of these living systems is through an analogy: thinking of sturdy molecular systems as furniture that is glued together.

Having hydrogen bonds is nature’s way of giving flexibility to structural elements.

It is certainly easier to separate two glued pieces of furniture at the glue joint by softening the glue with solvent than it is breaking down the wood and repairing that.

To take our furniture analogy one step further, having temporary bonds allows college kids to take the same furniture in their dorm room and create different arrangements that work for the roommates that have to share the living quarters.

The furniture elements have not changed; where and how you attach them has.

Temporary and moldable

More importantly, hydrogen bonds get created virtually instantly when necessary.

Let’s take spider silk as an example: the spider produces a mass of protein strands in its silk gland; these proteins are soluble in a soupy fluid in the spider’s silk-producing gland.

The protein strands are attached at one end, close to the opening of the gland. The rest of the strands are swimming free within the gland, like strands of pasta in a large pot of hot water**.

When the spider wants to use the silk (either to escape or make a web) it attaches the first portion of the joined protein strands to a stationary object, say a tree branch.The strands 5605470879_853ae43871_bthen pass through an increasingly narrow spigot at the entrance of the silk gland.

What is the result? the protein filaments are squeezed together in the micro-hair-width spigot tunnel and the excess water is removed.

A bunch of wet spaghetti pasta strands

This would be similar to grabbing a bunch of wet spaghetti pasta strands at one end with tweezers and then passing the lot through an ultra-thin funnel; the water would be squeezed out and the strands would stick together.

For the spider, passing the silk through the very narrow spigot 17940720972_42960bf40f_oencourages the virtually instantaneous formation of hydrogen bond links between the touching strands of molecules.

As the spider spools out the silk string, the protein strands zipper themselves together making one long silk thread.

Having the protein strands in a soluble state until they are ready to be used prevents congealed and tangled silk threads;

Snarled and knotted webs would bode poorly for survival for that species of spiders.

_______________________

Picture credits

  1. Steve Bittinger. Spider Web at Wyanbene campground, Deua National Park, near Braidwood, NSW, Australia. Flickr photo-sharing. Taken on April 5, 2010.
  2. L Church “Golden Silk Spider Web – Nephila clavipes” Flickr – Photosharing! taken on July 11, 2009
  3. Ronald Tagra. “Processing Abaca Fiber somewhere in Sogod, Southern Leyte. Abaca (aka Manila Hemp) is a kind of banana specie that bear less edible fruit but the trunk being harvested for its fiber”. Flickr – Photosharing! Taken on Nov 22, 2012
  4. Thomas Bruckner (From PLoS Comput Biol. 2009 Apr;5(4):e1000357). Hydrogen binding. Photo from Flickr – Photosharing. Uploaded July 11, 2014.
  5. James Niland. “Spider busy pulling sticky thread”. Flickr – Photosharing! Taken on April 10, 2011
  6. Will Anderson “Nephila Pilipes – Giant Orb Weaver Spider – Nakhon Si Thammarat – Thailand” Flickr – Photosharing! Taken on March 18, 2014

References

  1. Knight DP, Vollrath F. Spinning an elastic ribbon of spider silk. Philos Trans R Soc Lond B Biol Sci. 2002 Feb 28;357(1418):219-27.
  2. Keten S, Buehler MJ. Nanostructure and molecular mechanics of spider dragline silk protein assemblies. J R Soc  Interface. 2010 Dec 6;7(53):1709-21.

* Abaca fiber. also known as Manila hemp. Abaca is the strongest of natural fibers. The Philippines is the world’s largest source and supplier.

**  Speaking of cooking spaghetti, one way to test whether the pasta is cooked is to take one strand of spaghetti and throw it at the wall; if it sticks, the spaghetti is cooked! this is because enough of the starch has spread out/moisturized to allow hydrogen bonds to form between the molecules of the starch and those on the wall.

 

Juman Hijab

About the author

Juman is a retired physician after having been in clinical practice for more than four decades. Her lifelong interest has been in the chemistry of life.

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