Trigger 8: Non-coding RNA Flashcards
a non-coding RNA (ncRNA)
is an RNA molecule that is not translated into a protein
how much of transcriptional output is ncRNA
97-98%
ncRNA is probs not
part of the central dogma, due to it being non-coding
types of ncRNA
rRNA (ribosomal)
tRNA (transfer)
RNAi (interference)
two types of RNAi
miRNA and siRNA
miRNA
small RNA involved in regulation of expression
iRNA
small interfering RNA which activates molecules in RNA interference
ncRNA function to
regulate gene expression at the transcriptional ad post transcriptional level
two main groups of ncRNA involved in epigenetic processes
short ncRNA
long ncRNA
short ncRNA
<200 nts
long ncRNA
> 200 nts
both groups of ncRNA
are shown to play a role in heterochromatin formation, histone modification, DNA methylation, targeting and gen silencing
microRNAs are
small ncRNAs (22nts long)
miRNA do what to gene expression
repress gene expression
miRNA are involved in
development, differentiation, proliferation and apoptosis
how to miRNA exert their effect
by base pairing to complementary mRNA sequences
miRNA induce a silencing complex called
RISC
RISC
RNA-idncued silencing complex
mRNA complexed with RISC
cannot be expressed
miRNA expression is
tissue specific and highly regulated according to cells developmental lineage and stage
process of how miRNA exerts effect
1) pro-miRNA are transcribed
2) drosha processing produces pre-miRNA
3) pre-miRNA is exported out of the nucleus by Exportin-5
4) formation of RISC complex (mature miRNA)
5) binds to mRNA- causes translational repression
what does miRNA complex with
complementary to the 3/UTR of the target mRNA- inhibiting translation
