Amino Acid Pyrrolysine Flag: O Flag or Pyl Flag

The Flag for Pyrrolysine uses the colours red, cyan, green, and white.  This amino acid is not found in humans, but only in prokaryotes.  Since the R-Group has 10 Carbons, there are 10 dot (4+4+2=10).  The field is green since it is in a class of its own.  It has a ring structure, oxygen, and nitrogen. The nitrogens of the R-group outnumber the oxygens, thus it is a green colour rather than purple. The red and cyan stripe related to the number 15 in colour metrics.  And the letter O is 15th number of the alphabet and the single letter abbreviation for this amino acid.

This amino acid was recently discovered in the USA 2002 by Joseph A. Krzychi and Michael K. Chan.  Usually the codon UGA is usually a stop signal for making a protein, but for special bacteria and archaea, UGA codes for amino acid O.  Effectively this newbie amino acid is only 17 years old, as of 2019.  But in the big picture, it is an ancient building block (much older than than the modern human form) that has been used for millions of years by prokaryotes, especially those that make methane. Accordingly when people try to ignite their flatulence, they can thank these microscopic critters that live in your gut.