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Transcription - RNA pol copies 'coding strand' using non-coding…
Transcription - RNA pol copies 'coding strand' using non-coding strand as template
Gene structural elements :star:
Gene:
A region of DNA that codes for a discrete, hereditary characteristic
Exons:
Any region retained in mature transcript
Introns:
Present in pre-mRNA but removed via splicing during mRNA maturation
Promoter:
Region 5` of gene where RNA pol binds & initiates transcription
Enhancers:
DNA elements that increase transcription independent of their position & orientation
Initiation
RNA pol binds DNA "upstream" of transcription initiation site
Transcription proceeds in 5' to 3' direction
RNA pol separates DNA strands creating an unpaired region - transcription bubble
Template strands become available to read
Transcription Factors (TFs)
:star:
Form pre-initiation complex with RNA pol, TATA binding protein (TBP)
Regulated by
Co-activators: Increase transcription
Co-repressors: Decrease transcription
Co-regulators: Don't bind DNA directly
Regulation of estrogen activity :
Estrogen binds
estrogen response elements
(EREs)
associated with estrogen target gene
Inappropriate ER activity --> breast cancer
Elongation
Once transcription initiated,
bases added in 5' - 3' direction
at 20 - 50 nt/sec
Post transcriptional processing of pre-mRNA :star:
5' capping
Polyadenylation
Protects transcript from exonuclease degradation
Splicing
Introns removed