12. Gene Transcription & RNA Modification

regulatory sequences

site for the binding of regulatory proteins—influence rate of transcription

promoter

provides site where polymerase binds to begin transcription

terminator

specifies end of transcription

transcription factors

DNA-binding domains that give them the ability to bind specific regulatory sequences of DNA

(enhancer/silencer sequences)

template strand

the strand that is actually transcribed

coding/sense strand

opposite of template strand with a base sequence identical to RNA transcript

stages of transcription

initiation ➔ elongation ➔ termination

mRNA from

structural genes

rRNA & tRNA from

nonstructural genes

structural genes are

translated into polypeptides and proteins

nonstructural genes are

not translated; RNA is final product

snRNA (small nuclear RNA)

splices eukaryotic pre-mRNA.

component of a spliceosome

telomerase RNA

enzyme involved in the replication of eukaryotic telomeres

composed of RNA & protein subunits

bac. initiation

promoter functions as recognition site. transcription factor enables RNA polymerase to bind to the promoter. DNA is denatured into a bubble = open complex

bac. elongation/synthesis

RNA polymerase slides down the DNA in an open complex to synthesize RNAterm

bac. termination

causes RNA polymerase and RNA transcription to dissociate from the DNA

bac. promoters

DNA sequences that ‘promote’ gene expression—located upstream near transcription site

bac. RNA polymerase

catalyzes RNA synthesis

E. coli RNA pol. holoenzyme