Transcription Flashcards
How does methylation affect DNA transcription?
DNA Methylation (not to be confused with histone methylation) is a common epigenetic signaling tool that cells use to lock genes in the “off” position.
Which nucleotide is methylated to silence genes?
Cytosine
What are DNMT1, 3a, and 3b?
DNA methyltranferases
How do differential methylation patterns relate to cancer?
- DNA hypermethylation has been shown to silence tumor suppressor genes
- Cancer cell genomes have exhibited HYPOmethylation overall in comparison the healthy cells
- But hypermethylation of the genes involved in tumor cell invasion, DNA repair, regulation of the cell cycle, and other processes where silencing leads to metastasis
How do group transfers affect chromatin packing?
Acetylation - Loose packing and euchromatin
Methylation - Tight packing and gene silencing
What is the role of SWI/SNF in histone remodeling?
- SWI/SNF opens up DNA regions where transcription proteins, transcription factors, and co-activators bind to turn on gene transcription
- Absence of SWI/SNF results in inability of nucleosome to move farther and remain tightly aligned
What are enhancers?
- Sequencee of DNA which activator proteins bind to
- Their binding causes DNA to bend
Wha this the function of Protein complexes in binding of transcription factors?
Make it easier for RNA polymerase to bind
Differentiate the need of TFs in Bacteria and Eukaryotes for transcription.
Bacteria: an RNA polymerase and single GTF
Euks: An RNA polymerase and Multiple GTFs to form a TIC
Which strand is n enhancer on compared to the gene it modifies?
ICS-Acting: On the same strand of DNA
What is the major polymerase for transcription?
RNA Polymerase II
What provides the specificity for binding of RNA polymerase?
The promoter sequence
Describe the structure of the prokaryotic RNA polymerase.
3 Units:
Alpha
Beta: Forms core enzyme
Sigma: Promotor recognition
How does RNA polymerase choose the transcription start site?
Based on distance from consensus sequence
What are the two prokaryotic signal terminators?
Rho-Independent: Inverted CG repeats which form a hairpin and a 6 polyadenine tail;
Rho-Dependent: C-G hairpin loop; Requires Hexomeric ATPase with helicase activity “Rho”
- Rho moves toward 3’ end
- Rho binds C-Rich region “Rho utilization site”
- Unzips RNA f/ DNA and acts as RNA/DNA helicase
** NO ADENINE RICH REGION
