Transcription control and lncRNAs Flashcards
(32 cards)
Types of noncoding DNA sequences
ones that function in transcriptional regulation (promoters, enhancers, silencers, insulators)
non coding RNA genes
non coding RNA genes
make a functional RNA as their end product
lineage differentiation
process of cells developing specialised functions from a pluripotent precursor
what does RNA polymerase 1transcribe?
rRNAs involved in protein synthesis
what does RNA polymerase 2 transcribe?
all protein coding genes
snoRNA genes
microRNA genes
miRNA
siRNA genes
lncRNA genes
what does RNA polymerase 3 transcribe?
tRNA genes
RNA polymerase 2 structure and recruitment
12 subunit protein complex
recruited to target genes with GTFs and regulatory proteins in RNA pol 2 holoenzyme (complex)
cis regulatory dna sequences
promoters
enhancers
insulators
silencers
promoters
contain dna sequence motifs
ordered recruitment of GTFs to precisely position RNA pol 2
some contain TATA but not all
TFIIH
helicase activity
locations of enhancers and silencers
upstream or downstream from target gene
within introns or coding regions
can be distal
function of enhancers and silencers
modulate rate of promoter transcription
how distal cis regulatory elements work
TFs bind to specific motifs of cis regulatory sequences and interact with GTFs and RNA pol 2
contact co activators and co repressors>mediators that dont directly bind dna
DNA loop
enhancer elements
speed up rate of RNA pol 2 - GTF complex assembly
can modify chromatin structure
insulator elements
between enhancer and promoter
block action of distal enhancer on a promoter
barrier elements
insulators that stop spread of condensed chromatin sequences into domain of actively transcribed chromatin
non coding RNAs
transcribed but not translated into protein
functional rna as end product
TERC TERA
specialised functions and are involved in telomerase functions (maintaining ends of chromosomes).
housekeeping ncRNAs
rRNA, tRNA and RNAs involved in RNA maturation (snRNAs for splicing and snoRNAs for RNA editing
regulatory ncRNAs
splicing
miRNAs
siRNAs
lncRNAs
> 200nt in length
transcribed by RNA pol 2
Possess a polyA tail and 5’ 7-methylguanosine cap
in nucleus or cytoplasm
more tissue specific
how are lncRNAs characterised
location/tissue
genomic organisation relative to protein coding genes
sense lncRNAs
transcribed in same direction as nearby protein coding genes
can overlap with exons/introns
regulate expression and splicing
antisense lncRNAs
transcribed in opposite direction
overlap introns/exons on opposite strand
gene silencing,
