Transcription Flashcards
why is mRNA used?
as an intermediate and to amplify gene expression, does not degrade in the cytoplasm
why are transcription factors used?
because RNA polymerase cannot directly bind to the DNA
what do transcription factors bind to?
regulatory elements in/near the promotor gene or further away
what are basal promotor elements?
regulatory elements in/near the promotor
what are proximal promotor elements?
regulatory elements 100-200 bps away from the promotor
what are cis acting elements?
sequences present on the same DNA molecule as the gene they effect
what is an example of a basal promotor element?
TATA box
what is an example of a proximal promotor element?
GC box and CCAAT box
why is only RNA polymerase II used?
pol I and III used for rRNA
what characteristics do promotors need to have for RNA pol II to bind?
have a core promotor and an upstream element
how is RNA polymerase II a holoenzyme?
does not act alone as it is made up of different proteins including the enzyme, transcription factors and regulatory proteins
what does FACT do?
partially disassembles the nucleosomes upstream by temporarily removing two of the histones out of the way
what is allosteric termination?
polyadenylation tail signal sequence added on the end of mRNA and when this is transcribed, it releases the mRNA
how does the tail signal make the mRNA more prone to dissociate?
causes a conformational change
how does torpedo termination work?
the transcribed mRNA is longer than the actual gene, so it is cut at the cleavage site so that it is completed and released
