Definitions for "Reading frame"
Keywords:  codon, triplet, mrna, nucleotide, gca
The set of nucleotide pairs coding for one particular amino acid in the sequence of several thousand nucleotides in a gene; addition or deletion of one or two nucleotide pairs shifts the reading frame from that point to the end of the molecule.
The particular nucleotide sequence that starts at a specific point and is then partitioned into codons. The reading frame may be shifted by removing or adding a nucleotide(s). This would cause a new sequence of codons to be read. For example, the sequence CATGGT is normally read as the two codons: CAT and GGT. If another adenosine nucleotide (A) were inserted between the initial C and A, producing the sequence CAATGGT, then the reading frame would have been shifted in such a way that the two new (different) codons would be CAA and TGG, which would code for something completely different. See DNA, Codon, Mutation, Nucleotide.
In a protein-coding mRNA, the translation machinery has to start at a particular point in order to read off the correct sets of three nucleotides (codons) as it moves along the RNA. There are three possible reading frames in any sequence, only one of which usually encodes a functional protein.