Gene Regulation Flashcards
Purpose of Gene Regulation
- Give cell specialized role
- Gene product dosage
- Nuclear Envelope
- Respond to changing environmental stimuli
- Different developmental stages
Always transcribed/expressed
- Gene product continuously needed to run the cell
ex. GAPDH in glycolysis, rRNA genes, Actin
Housekeeping Genes (Constitutively expressed)
Transcription and expression is more regulated.
- Transcribed and translated in response to the needs of the cell.
ex. immune response, development, vasodialators/constrictors, HOX
Conditionally expressed genes (Facultatively expressed)
Where does transcription occur?
- Chromosome territory
- Interchromosomal domain
- Transcription factory
Each chromosome exists in a defined area of the nucleus.
Chromosome territory
Areas of nucleoplasm between chromosomes
-Space
Interchromosomal domain
Clusters of transcriptional machinery
Transcription factory
- Is essential for transcription
- When bound by GTFs, recruits polymerase and causes basal transcription.
- Other elements fine tune transcription
Core Promoter
“next to gene”
consensus sequence
Cis-acting sequence
“from someplace else” (away from gene)
Trans-acting sequence
Regulatory segments of the eukaryotic gene
-Set of cis acting elements are bound by trans acting factors
Regulatory segments of the eukaryotic gene contain:
-Combination of coordinates strength of expression of that gene (can turn up or down gene expression)
- Core promoter
- Proximal elements—close
- Distal elements—far
- Enhancers
- Silencers
Regulatory Elements
Enhancers
Silencers
Bound by activators
Cis regulating element
-When bound, increase transcription of the gene
Enhancers
Bound by repressors
-When bound, transcription is decreased and gene expression is repressed.
Silencers
Regulation at the transcriptional level is upstream or downstream from the +1 site?
Upstream
Have 2 major domains:
- DNA binding domain
- Transcription activation domain
- Changing shape
Activators
Subset of enhancers
- binding allows for the cell to respond to enviornmental changes by expressing genes involved in that response
ex. ARE (antioxidant response element)
Response Elements
Have opposite role of activators
-Decrease transcription
Repressors
In response to injunctions from activators, these factors position RNA pol. at the start of transcription and initiate the transcription process
GTFs (General transcription Factors)
Each gene has a specific set of regulatory elements that are bound by specific regulatory proteins
-More efficient because no need for more activators
Combinatorial gene regulation
To measure expression
Measure amount of products:
1. RNA
2. Protein
Reporter System–located downstream from promoter of interest
Histone core is moved so that the gene is accessible to transcription.
-Sliding exposes DNA
Chromatin Remodeling
One gene can encode more than one protien because different combinations of exons are spliced together
Alternative Splicing
