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        | 異論サイドです。Ben LewinのGENES XIIから引用します。openがclosedもしくはblockedと対比される意味で使われていることがわかると思います。 
 If the genetic code is read in nonoverlapping triplets, there are three possible ways of translating any nucleotide sequence into polypeptide, depending on the starting point. These are called reading frames. For the sequence
 
 ACGACGACGACGACGACG
 
 the three possible reading frames are
 
 ACG ACG ACG ACG ACG ACG
 CGA CGA CGA CGA CGA CGA
 GAC GAC GAC GAC GAC GAC
 
 A reading frame that consists exclusively of triplets encoding amino acids is called an open reading frame (ORF). A sequence that is translated into polypeptide has a reading frame that begins with a special initiation codon (AUG) and then extends through a series of triplets encoding amino acids until it ends at one of three termination codons (UAA, UAG, or UGA).
 A reading frame that cannot be read into polypeptide because termination codons occur frequently is said to be closed, or blocked. If a sequence is closed in all three reading frames, it cannot have the function of encoding polypeptide.
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