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
What section of mRNA does micrRNA usually bind to?
3’ untranslated region
Are microRNAs coded in the genome?
Yes
Are siRNAs coded in the genome?
No
How are siRNAs generated
Exogenously
What are the 3 post-translational modifications we learned about
Phosphorylation
Ubiquitination
Proteolitic processing
How do siRNAs work?
They’re a perfect match to one specific mRNA target and cleave it
How does proteolytic processing regulate protein production
Post-translational. Protein cleavage used to convert enzymes from inactive to active form, ensure activity/function at certain time/location
What regulates translation initiation
Phosphorylation of eIF2
Cannot associate with ribosome –> no translation
How does phosphorylation regulate protein production
Post-translational. Addition of phosphate group to AA can activate, deactivate, or change a protein’s behavior
How does ubiquitination regulate protein production
Post-translational. Addition of a small protein (ubiquitin) to lysine residues. Usually marks protein for degradation
Example of therapeutic use of gene regulation
Sickle cell anemia – microRNA cleavage of protein that suppresses fetal hemoglobin (we want fetal hemoglobin to stay because it’s not attacked in the disease process)
Example of diagnostic use of gene regulation
Dysregulation of microRNA is associated with certain diseases
Biomarker:
Measurable substance found in blood/body fluids/tissues that is indicative of a specific state (disease, infection, exposure)
What is the primary control for gene regulation
Transcriptional
