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12 Cards in this Set
- Front
- Back
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What are the roles of the 3 Eukaryotic RNA polymerases |
1.RNA polymerase I=transcribes genes that encode for rRNA 2.RNA polymerase II=transcribes genes that encode all proteins and micro-RNAs 3.RNA polymerase III=treanscribes genes that encode tRNAs as well as some other small RNAs |
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define gene expression |
gene expression= the production of an active gene product( ex protein, mRNA) |
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Compare and contrast gene expression in prokaryotes to eurkayotes |
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describe the possible steps at which gene expression can be regulated in eukaryotes |
1.intitaion of transcription 2.transcript processing(including alternative splicing) 3.export of mRNA from the nucleus 4.translatability of the message 5.localization of protein products in specific organelles in the cell 6.post-translational modification to the protein,(e.g. cleavage, phosphorylation....) |
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describe the 3 types of cis-acting elements: promoters promoter-proximal elements enhancers |
promoters- close to the gene, always including the initiation site for transcription (aka +1), sometimes contains TATA box, sometimes contain DPE( downstream promoter element), binding RNA poly to TATA or DRE allows fro basal level transcription Promoter-proximal elements- sequences 200bp upstream of promoter that bind transcription factors.(GC box CCAAT boxes), Enhancers- are regulatory sites that can be quite distant from the promoter,binding of enhancer increase or decrease level of transcription |
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Describe the method to detect promoters and enhancers |
can identify promoters and enhancers by making reporter constructs with a resumed regulatory region hooked up to a reporter gene(ex.LacZ GFP) -used in vitro mutagenesis across the regulatory region and then reintroduce the reporter constructs into the genome by transformation, look for increase or decrease level of transcription |
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define transcription factor, including basal factor or TAFs |
transcription factors- trans-acting proteins control transcrition intitaio. basal factors assist in binding of RNA polymerase II to the promoter and the initiation of a low level of transcription called basal transcription TAF= TBP- associated factor ( TBP=TATA binding protien) |
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describe how DNA binding sites can be found analyzed by chromatin immunoprecipitation (ChIP) techniques |
ChIP=The use of antibodies to isolate specific regions of chromatin and to identify the regions of DNA to which regulatory proteins are bound. 1.treat proteins so they can cross-link with DNA 2.break chromatin into pieces 3. add antibody to target protein and purify 4.reverse crosslink to separate DNA and protein 5.amplify and sequences DNA segment of interest |
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compare and contrast activators and co-activators make into multple questions |
Activators -increase transcription activity by binding to an enhancer element and directly or indirectly interacting with basal factors at the promoter |
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describe the role of a Mediator |
Mediator = one of the most important protein coactivators, a large multiprotein complex composed of 25-30 proteins -the mediator does not bind to DNA but serves as an essental bridge between promoter and enhancer for many of the pol II promoters in eukaryotic organisms |
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describe the common domains of transcription factors |
d |
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compare repressors and co-repressors |
Repressors Co-repessors |
