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small and long RNA
Advanced Genetics
Question | Answer |
---|---|
Antisense RNA | Made from complementary DNA strand that sits opposite a protein-coding gene on the double helix. |
What can antisense RNA do? | They can intercept the messenger RNA transcribed from the gene, preventing the mRNA from being translated into protein. |
RNAi | used by eukaryotes to limit invasion of foreign genes. Triggered by double stranded RNA molecules. dsRNA are chopped by Dicer to make siRNA and miRNA. |
Ribosome types found in bacteria and eukaryotes | rRNA, mRNA, rRNA |
Ribosome types found in eukaryotes | snRNA.snoRNA,miRNA,siRNA,piRNA |
Ribosome types only in prokaryotes | crRNA |
RNA located in the cytoplasm only | rRNA and tRNA |
rRNA function | structural and functional components of the ribosome |
RNA located in the nucleus and cytoplasm | mRNA,miRNA,siRNA,piRNA |
RNA located in the nucleus only | snRNA, snoRNA |
mRNA function | carries genetics code for proteins |
tRNA function | Helps incorporate amino acids into polypeptide chains |
snRNA function | Processing of pre-mRNA |
snoRNA function | Processing and assembly of rRNA |
miRNA funtion | degradation of mRNA, inhibition of translocation, chromatin modification |
siRNA function | degradation of mRNA, inhibition of transcription, chromatin modifications |
piRNA function | suppresses the transcription of transposable elements in reproductive cells |
crRNA function | assists destruction of foreign DNA |
RNA polymerases found in all eukaryotes | RNA pol I, RNA pol II, RNA pol III |
RNA polymerase only in plants | RNA pol IV, RNA pol V |
RNA pol I transcribes | Larger rRNAs |
RNA pol II transcribes | Pre-mRNA, some snRNA, snoRNA, some miRNAs |
RNA pol III transcribes | tRNA. small rRNA, some snRNAs, some miRNA |
RNA pol IV transcribes | some siRNA |
RNA pol V transribes | RNA molecules taking part in heterochromatin formation |
miRNA and gene silencing | inverted DNA repeat, transcription, pri-miRNA with hair pin, cleaving of ends, add dicer, add Argo, creation of RISC, imperfect base pairing, inhibition of translation |
siRNA and gene silencing | dsRNA, add dicer, get siRNAs, add Argo, create RISC, perfect base pairing mRNA, cleavage and degradation |
Origin of siRNA | mRNA, transposons, or virus |
Origin of miRNA | RNA transcribed from distinct genes |
siRNA comes from the cleavage of | RNA duples or ssRNA that forms long hairpins |
miRNA comes from the cleavage of | ssRNA that forms short hairpins of dsRNA |
How many nt is siRNA and miRNA? | 21-25nt |
siRNA targets | genes from which they were transcribed |
miRNA targets | genes other than those from which they were transcribed |
How many perfect base pairs do siRNA need? | 7 |
lncRNA length | larger than 200nt, open reading frame |
lncRNA function | Chromatin interaction, protein interaction, regulating other RNAs in relation to metabolism, very specific to a cell type. normally kept off through methylation and only turned on in certain circumstances |
lncRNA and chromatin interation | change shape of chromatin directly, recruit transcriptional regulators. |
lncRNA and protein interaction | modulate interaction if 2 proteins by binding to them. promote or prevent interaction |
lncRNA and metabolism | miR will bind to lncRNA therefore miR can't bind to mRNA and degrade it. can also help with stabilization and splicing. |
X inactivation/silencing | one X becomes barr body |
Formation of barr body | Xist is a lncRNA (17000nt), it coats the chromatin of the inactive X. Is regulated by Tsix |
Tsix | antisense to Xist, prevents Xist from coating active X. |
Xist promotes | H3K27me3 and other histone methylation and deacetlyation to create barr body. Polycomb proteins make Polycomb repressive complex helps H3K27me3 and deacetlyation. many CpG are methylated leading to permanent silencing of inactive X |
RISC | Induced silencing complex. argonaute protein |
Piwi interacting RNAs | 24-30nt, derived from long ssRNA, no dicer, piRNA and Piwi protein suppress the expression and movement of transposons in the germ cells of animals |
crRNA | Encoded my DNA sequences found in bacteria and archaeal genomes. clustered regularly interspaced short palindeomic repeats. role in defense against the invasion of specific foreign DNA |