Amino Acid Selenocystine: U Flag or Sec Flag

The flag for Selenocystine uses the colours orange, red, and black.  The single black dot represents the lone carbon in the R-Group.  The orange and red stripe refer to the Selenocystine's single letter abbreviation: U.  The stripes indicate the number 21 and U is the 21st number of the alphabet.  Red represents 1 and orange represents 2, together they make 21.

The orange field is unique for amino acid flags, since only one R-Group uses this rare transitional element.

Amino Acid U was discovered by a New Yorker, Thressa Stadtman sat the National Institutes of Health. Its discovery dates back to 1954 but name dates to 1959.