Seeking clearcut explanation regarding ORF(Open reading frame) and Exon. Some of the authors defination are complication. Like some says ORF is a stretch of DNA having Start codon at one and stop codon at another end. While some says ORF is just a coding DNA present withing start codon (AUG) and Stop codon (TAG, TAA, or TGA). All these make complication in my overthinking brain. Then what about Exon and Intron? Coding DNA...
An ORF is a region of DNA that starts with a start codon and ends with a stop codon. Within an ORF are introns and exons.
Exons are the coding part of the transcribed DNA
When DNA gets transcribed in eukaryotes you get splicing of the mRNA resulting in the removal of introns and sometimes even exons. This can result in transcripts with alternative start sites, frame shifted exons, shuffled exons and alternative stop sites. This means that a single stretch of DNA can generate many alternative ORFs.
These are two different thing based on their function and usage. Thus, these should not be compared.
It can be seen as ORF is HOW the stretch of DNA is being read by the polymerase, frame 1, 2 or 3 / longest sequence without internal stop codons
While
Exon is what is it and WHAT is being read or what is the information which will go to the translation process.
Thank you everyone for your deep insight and clarification of my doubt. Kristin M. Adams @Robert Adolf Brinzer Abhijeet Singh
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