Subject: How do introns exist?

We are the students in the Molecular Biology class at John F.Kennedy High 
School. We've learned about introns and exons in the class. We know that both 
RNa strand and the DNA strand contain sequences of nucleotides that do not code 
for the amino acids in proteins. These are the introns. We are curious about the 
introns. We don't understand how do introns exist.

Re: How do introns exist?