Regulatory Regions and Introns Flashcards
What are promoters - 1 and what do they determine ?
- They are regulatory regions of DNA upstream of a gene, which provide a control point for regulated gene transcription
- Determine when and where gene is expressed
What is the core promoter and where is it located ?
Is the minimal portion of the promoter required to properly initiate transcription.
Located around position -34.
What is the proximal promoter and what’s it called ?
Is the proximal sequence upstream of the gene that contains primary regulatory elements. Located around position -250
What is the distal promoter ?
Is a very ill-defined area which can range from beyond the 5’ end of the gene up to and even into the next gene.
What are 3 other control elements ?
Enhancers, silencers and insulators
What is an enhancer ?
Is a short region of DNA that can bind activator proteins to trigger the transcription of a gene.
What are 6 reasons why enhancers are important ?
1) Important role in the evolution of species
2) Developmental biology - development, differentiation and growth of cells and tissues
3) Invertebrate segmentation - creation of different zones
4) Vertebrate patterning - Body axis anteroom-posterior and left-right
5) Developmental robustness - survival of fruit flies when environmental disturbances take place
6) Developmental mechanisms - limb development, wing pattern evolution
What are promoter silencer ?
-DNA sequences that bind repressor proteins that inhibit expression
-Act in the opposite way to enhancers
-Can reduce or totally inhibit expression
-Sequence can be anywhere in the promoter
- Binding of repressor protein inhibits RNApol complex formation
- Can be caused by bending the DNA
How is the neuronal- restrictive silencer factor a promoter silencer example ?
- Its produced by the REST gene
- Repress the transcription of neuronal genes in non-neural cells
- When the silencer represses REST, NRSF is also inhibited - which allows the transcription of neuronal genes.
What are promoter insulators -1 ?
- ## Are genetic boundary elements that block the action of enhancers
What does promoter insulators-1 determine ?
They determine the set of genes and enhancer can influence
What do promoter insulators-1 stop enhancers doing ?
Working on adjacent genes
Where are promoter insulator-1 present ?
They are present at the boundary of topological association domains which divide the chromosome in “ chromosome neighbourhoods”
How do promoter insulator-1 act ?
Act by loops
What do promoter insulators-1 prevent the spread of heterochromatin from ?
Froms a silenced gene to an actively transcribed gene
