RNA, cDNA, and DNA - RNA, cDNA, and DNA (Nov/01/2005 )

Hi,
I was wondering if there was a difference in the sequences between RNA, cDNA, and DNA?
I understand that the T is changed to a U in RNA.... but does the actual sequence change?
Is there a way to find out where the intron and exons start in cDNA?

Thanking you in advance,
Snoopy

snoopy, you won't find introns in cDNA

the sequence should the same for all, except that DNA has introns added...and the RNA sometimes is shorter when other modifications are made after transcription

Thankyou.

In real time PCR, papers often state that their primers span across exons.... does this mean they cross where one exon ends and another begins?
How would primers be designed if you were looking at the effect of an intron on transcription?

Snoopy,

Yes, because mRNA doesn't contain introns (as mentioned earlier), one designs primers so that one spans where one exon begins and another ends. This is to hopefully eliminate the possibility that your PCR product could include genomic DNA contaminants rather than just cDNA (reverse transcribed from RNA). As for the effects of an intron on transcription, I'm not sure I quite understand what you mean, so will answer off my best guess. If you were to, for example mutate an intron in your genomic DNA and this were to affect transcription, you would still analyze mRNA (without introns) because this is the product of transcription. Does this answer your question?

LabGirl