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A portion of a DNA that codes for a section of the mature messenger RNA from that DNA, and is therefore expressed (“translated” into protein) at the ribosome. [ex- + on]
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ex·on 'ek-.sän n a polynucleotide sequence in a nucleic acid that codes information for protein synthesis and that is copied and spliced together with other such sequences to form messenger RNA compare INTRON
ex·on·ic ek-'sän-ik adj
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ex·on (ekґson) [expressed (sequence) + -on] a coding sequence in a gene; see also intron.Medical dictionary. 2011.