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22 Cards in this Set
- Front
- Back
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What are types of functional RNA? |
ribozymes long non-coding RNAs miRNAs |
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What is the initiator codon? |
start of translation DNA: ATG RNA: AUG |
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What is the termination codon? |
TAA, TAG, TGA - stop translation |
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What are introns? |
non-coding, removed |
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What is cleavage-polyadenylation site? |
transcript cut at this site and about 200 As are added - defines end of last exon included in mRNA |
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What controls the expression of genes? |
interaction of trans-acting transcription factors with cis-acting DNA sites |
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What are cis-acting sites? |
promoter - adjacent to transcription start site with site that assembles RNA polymerase 2 complex enhancer - act over long distances to bind trans-acting transcription factors that positively influence gene transcription silencer - act over long distances to bind trans-acting transcription factors that negatively influence gene transcription |
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What two parts are trans-acting factors made of? |
activation domain DNA-binding domain |
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What are enhancers? |
- increase rate of transcription initiation - cluster of transcription factors binding sites - alter chromatin or influence recruitment of RNA pol II initiation complex - upstream, downstream or within introns |
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What are silencers? |
same properties of enhancers but negative effect to repress gene expression |
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What are co-activators? |
- exert positive influence on transcription - interact with transcription factors - bridge between DNA binding proteins and pol II initiation complex - act via histone acetyl transferase (CBP/p300) |
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What are co-repressors? |
- negative influence on transcription - block bridges between DNA binding proteins and pol II initiation complex - histone deacetylase (HDAC1,2,3) |
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What do transcription factors do? |
- influence assembly of RNA polymerase II and associated factors - influence rate of transcription initiation - interact with cis-acting site |
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What is the combinatorial model of gene regulation? |
interaction of multiple trans-acting transcription factors with multiple cis-acting binding sites determines tissue-specificity, timing and level of gene expression |
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What is the domain structure of nuclear receptors? |
variable region (transactivation) - DNA binding region w/ Zn fingers - ligand binding region |
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What is the pathway for a type 1 nuclear receptor to bind DNA? |
Ligand binds to NR NR dissociates from chaperone NR dimerizes/enters nucleus NR binds to cis-acting sites (hormone response element = HRE) of genes NR recruits co=activators and RNA polymerase |
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What is the pathway of a type II nuclear receptor? |
NR heterodimer bound to HRE in nucleus Associated with co-repressors Ligand binds Co-repressors dissociate Co-activators bound to NR and recruit RNA polymerase Activate target gene transcription |
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What can mutation of hepatocyte nuclear factor 4 alpha (HNF4alpha) lead to? |
atherosclerosis diabetes drug metabolism problems cancer OTC deficiency MCAD deficiency hypoxia thrombosis hemophilia |
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What are the steps to Nuclear Factor-kappaB (NFkappaB) activation? |
- p50/relA heterodimer bound to inhibitor IkappaB in cytoplasm - stimulus targets IKK complex - IKK complex phosphorylates IkappaB - phosphorylated IkappaB polyubiquitinated - IkappaB degraded by 26S proteosome - NFkappaB(p50/relA) translocates to nucleus and binds cis-acting site (NFkappaB RE) - RNA polymerase II and associated factors recruited for transcription |
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What stimulation can activate NFkappaB? |
LPS viruses IL-1 TNFalpha chemicals oxidative stress ionizing radiation |
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What kind of gene is NFkappaB? |
pro-survival anti-apoptotic |
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What is NFkappaB relation with cancer? |
Can be activated during anti-cancer strategies - cause cancer cells to be pro-survival Companies focusing on blocking NFkappaB in cancer cells |
