Completed genome sequences allow every open reading frame (ORF), the part of a gene that is likely to contain the sequence for the messenger RNA and protein, to be cloned and expressed as protein. These proteins are then purified and crystallized, and then subjected to one of two types of structure determination: X-ray crystallography and nuclear magnetic resonance (NMR).  The whole genome sequence allows for the design of every primer required in order to amplify all of the ORFs, clone them into bacteria, and then express them.  By using a whole-genome approach to this traditional method of protein structure determination, all of the proteins encoded by the genome can be expressed at once.  This approach allows for the structural determination of every protein that is encoded by the genome.