Gene Regulation Flashcards
Gene regulation:
how a cell controls which of its genes are expressed
What is the primary control point for most proteins
Transcription
How do regulatory proteins work
alter chromatin structure, control assembly of transcription machinery
Where do regulatory proteins bind?
To DNA outside of promotor sequence (control elements)
Where do regulatory proteins bind?
To DNA outside of promotor sequence (control elements)
Activators:
Bind to DNA sequences called enhancers
Attract and position general transcription factors & RNA polymerase so that transcription can begin
How do activators work
-physically recruit transcription material to appropriate site
-recruit proteins to modify chromatin to make it more accessible
(can do one or both!)
Repressors:
Bind to DNA sequences called silencers
Block the general transcription factors & RNA polymerase
How do repressors work
-physically block activator proteins so they can’t recruit transcription machinery
-recruit proteins that modify chromatin to make less accessible
(can do one or both)
What is a mediator
Complex of proteins that serve as intermediary between:
-gene regulatory proteins
-general transcription factors
-RNA polymerase
What type of control are micro RNA and short interfering RNA examples of
Post-transcriptional control
MicroRNA action
-Transcribed –> folds into hairpin
-Processed by Drosha
-Exported into cytoplasm & processed further by enzyme dicer
-Binds to a group of proteins and one strand is degraded
-Then binds to mRNA
What enzyme processes microRNA
Drosha
If the mRNA and microRNA match perfectly then…
mRNA is chopped up
If the mRNA and microRNA don’t match up…
Translation is limited
