In the process of DNA Replication, why are introns longer + bigger than exons?

Answer 1

introns are longer because they have all the non-usuable excess genetic information not needed for protein synthesis

Answer 2

They are and they aren't. You have to look at the larger picture.

Most single-celled organisms have very few and small introns. But then to a cell which divides every few minutes, replicating DNA can be a pretty expensive comparatively.

Most multicellular organisms have lots of introns. By and large cellular replication is not one of their major energy costs. In that sense introns are like vestigal organs... so long as they're not really in the way there's not much harm in having them around. Perhaps they'll even come in useful someday. Some introns are even beneficial immediately - certain intron sequences can act to make sections of DNA more stable, for example.

So for us, introns make up 90% of our DNA simply because it's no big deal to copy ten times as much DNA as we actually need. For a bacterium, such a proposition is out of the question.

Answer 3

the introns are longer beacause later they need to split up and are removed