Growing Glycine Crystals

Chemists from New York University and St. Petersburg State University have been observing the growth of crystals of hippuric acid, a derivative of the amino acid glycine, and have discovered a new crystal growth phenomenon, a crystal that continually changes shape as it grows!

As molecules were added to the end of fine crystalline needles, stresses built up at the tips of the crystals resulting in a helical twist, just like you find in DNA's helix.
The twisiting process was reversed when the crystals thickened from the opposite end of the growing tip, ie, the crystals stiffened, undoing the twisted formations because the elasticity of the crystals decreases as they become thicker and this squeezes out the deformations formed at the growing tip.
The competition between twisting and untwisting creates needles with a rainbow of colours, characteristic of tightly wound helices and untwisted ribbons.

Reference:
New York University (2010, July 17). Chemists grow crystals with a twist -- and untwist. ScienceDaily. Retrieved July 19, 2010, from http://www.sciencedaily.com­ /releases/2010/07/100716125641.htm

Study Questions

1. What is the abbreviation for glycine?
2. Give the formula for glycine.
3. Why is glycine considered to be an amino acid?
4. Explain why glycine would be considered to be amphiprotic.
5. Write an equation to show how glycine could act as an acid.
6. Write an equation to show how glycine could act as a base.
7. Write an equation to show the formation of a cation from glycine in acidic solution.
8. Write an equation to show the formation of an anion from glycine in basic solution.
9. Compare the description of crystal growth as given in the article with what we consider to be the more "traditionally accepted" view of crystal growth.