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Protein Structure

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A Rocking Discovery

Can we turn milk into stone?

Credit: rkramer62
Source: http://www.flickr.com/photos/rkramer62/6233679473/sizes/m/in/photolist-auReJi-8KsKeK-bhrzLn-7PVYxj-87Dcpj-86swSa-a4ieh3-dsQ6bt-bQga2P-acT5mh-dUM67t-ah1ycp-8y2qwZ-aqF8d3-9BJ9sc-7FG1Ew-9qSaTB-9qSbqp-9qVbi1-9qSbZg-9qSazx-c4C1Qd-ah41zb/
License: CC BY-NC 3.0

[Figure1]

In milk is a substance called casein.  It is a family of phosphoproteins that makes up to 80% of milk.  However, it can also be used to make glue, paint, plastics, and other useful materials.  Before plastic was invented, casein was used to make all sorts of useful objects.  You can remove casein from milk by heating milk and adding one tablespoon of white vinegar for every cup of milk you are converting.  This will separate out the casein.  Mix until you see chunks of white.  Strain out the curds and try to remove as much water as possible.  In addition to straining, place the curds on paper towels and try to remove more water.  While still in a malleable form, shape the curds into a mold or any shape of your choosing.  Now, wait for it to harden (forty-eight hours should be more than enough).   Watch the video below to see it in action.  Good luck!

Creative Applications

  1. Why is casein so useful?
  2. What about casein’s structure allows it to become so hard?
  3. Why has plastic been substituted in for casein?

Resources:

http://www.youtube.com/watch?v=VFvik_THcNQ

http://en.wikipedia.org/wiki/Casein

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