Question

why is a single intron larger than a exon?

Answer 1

Exon's contain all the coding information for proteins. So their size is constrained by the actual size of the protein. Introns contain some regulatory elements, and lots of other noncoding DNA. Things like transposable elements (basically little chunks of DNA that copy themselves into other pieces of the genome) can insert into introns with no ill effects. Overtime this can increase the size of introns, while the exons are still constrained by the size of the protein they encode.

Answer 2

are you saying that one exon(chunks of RNA) is smaller compared to the protein it was destined to create? AND ARE you also saying that a intron have parts of them that copy or dupicate to add to the intron itself to make its size increase voluminously?

Answer 3

I'm not saying exons are smaller than the protein they code for. I'm saying that exon size is limited, total size of all the exons in a gene will always be 3 times the number of amino acids in that protein. so they cannot grow larger without changing the protein. On the other hand introns don't code for protein so they are not limited by teh protein's size. And yes there are parts in introns that copy themselves (they exist in all parts of non-coding DNA, not just introns). They are called transposable elements or jumping genes. But any other kind of insertional mutation can increase intron size as well.

Answer 4

BY NON CODING DNA , U MEAN EXONS TOO RIGHT?