Answer:
DNA in eukaryotes have introns which are the non-coding sequences and are spliced out of primary transcript. They are not present in mature mRNA.
Step-by-step explanation:
The reading frame of 50 or more nucleotides without any termination codon in between is called an open reading frame. The long open reading frames mostly represent protein-coding genes.
Hence, long open reading frames are searched for in order to find the genes. The presence of introns in eukaryotic DNA does not allow the application of this approach to find genes in eukaryotes.
The post-transcriptional modification of the primary transcript removes the introns. Hence, a mature mRNA does not have introns. Therefore, introns do not contain open reading frames.