And this is not true in prokaryotic cells because they don't contain the introns. And that's exactly why transcription and translation can take place at the same exact time as we'll discuss in more detail in future lectures. Now, on average in humans, a human gene contains about eight intros. But for those genes that are very, very large, for example, tens of thousands of nucleotides long, we can have as many as hundreds of these intros in a given gene. Now, the question is once the eukaryotic cell actually synthesizes this premRNA molecule, so this mRNA molecule that is not in its fully functional and modified form is commonly known as the precursor mRNA, the pre mRNA or the primary mRNA. And so once we form the primary mRNA molecule how exactly do we modify this molecule and at what stage do we actually take out these introns?