Work went pretty quickly after that, and by 1965 the genetic code was in hand. It is reproduced for your fun and amazement in Table 1. The table is easy to read. If you want to find out which three nucleotides code for, say, phenylalanine, you locate pheylalanine on the table (upper left corner). Read the first nucleotide from the left colum, the second from the top row, and the third from the right column. You should come up with UUU (Nirenberg and Matthaei did). Molecular biologists say that UUU is a codon for phenlyalanine.

second letter

FIRST LETTER	U	C	A	G	THIRD LETTER
U	Phenylalanine Phenylalanine Leucine Leucine	Serine Serine Serine Serine	Tyrosine Tyrosine Stop Stop	Cysteine Cysteine Stop Tryptophan	U C A G
C	Leucine Leucine Leucine Leucine	Proline Proline Proline Proline	Histidine Histidine Glutamine Glutamine	Arginine Arginine Arginine Arginine	U C A G
A	Isoleucine Isoleucine Isoleucine Methionine	Threonine Threonine Threonine Threonine	Asparagine Asparagine Lysine Lysine	Serine Serine Arginine Arginine	U C A G
G	Valine Valine Valine Valine	Alanine Alanine Alanine Alanine	Aspartic Aspartic Glutamate Glutamate	Glycine Glycine Glycine Glycine	U C A G

Table 1. The Genetic Code. It's easy to read if you follow the directions in the text.