Thread: junk DNA and transcription

stemming from my 'introns' thread...

when RNA polymerase is transcribing a DNA strand, does it just skip the segments of junk DNA? or is there no junk DNA within a gene segment, so that the polymerase can just transcribe whole segments and doesn't have to skip over certain areas?

I am loving your questions! Finally a topic I know way too much about!

Transcription starts at a promoter (or a nick, but that is a different story). When RNAP (RNA polymerase) binds along the DNA it will either search until it finds a promoter, or be recruited to a promoter. The transcription does not begin until the RNAP is securely on the promoter.

The 'junk DNA' does not get transcribed. It kind of depends on what your definition of 'junk DNA' is.

You must remember that lots of genes overlap. What the intron is for one gene may very well be an exon in another.

If the RNAP stops transcription it will simply fall off the DNA and start again elsewhere.