RR14 Flashcards
What is dsRNA? What is its effect/function?
- Double stranded RNA
- Plays a role in biological processes, gene regulation, and is
extremely stable - It harnessed machinery that was not there before
What is the effect of introducing a specific transgene?
Can introduce specific transgenes to make loop that corresponds to specific target we want to be rid of. (fold back on themselves)
What is the result of introducing a transgene into a fly?
Normally red eyes due to white. If we eliminate the white gene, it gives white eyes. Introduce a snap back, can copy white eyes and induce genetic change.
What happens if we introduce a transgene into a plant?
It gives mRNA and ends up with multiple stem cells.
What happens if we introduce small interfering RNAs into mice?
If we introduce small interfering RNAs, phenocopy the diseases by eliminating siRNAs introduced early (what normally happens).
Can now introduce asRNA or siRNA to recap. phenotype of disease.
What is the function of a Dicer?
Chops RNA up into microRNAs. Used in C. elegans.
How does RISC work? (RNA inducing silencing complex)
It is a multiprotein complex that incorporates one strand of a small interfering RNA (siRNA) or micro RNA (miRNA). RISC uses the siRNA or miRNA as a template for recognizing complementary mRNA. When it finds a complementary strand, it activates RNase and cleaves the RNA.
- Dicer chops dsRNA into fragments
- Fragments are bound by Argonaute protein in RISC
- Helicase unwinds using ATP hydrolysis, siRNA is now small single stranded fragment
- ssRNA targets an mRNA
- this new complex is then cleaved to be degraded
What is the difference between RNAi vs microRNA?
microRNA:
- mRNA destabilization
- translation inhibition
- interacts with RISC
- not 100% complementary
- family of molecules that helps cells control the kinds and amounts of proteins they make. That is, cells use microRNA to help control gene expression
siRNA:
- mRNA degradation RNai
- 100% complementary
- sequence specific supression
- double-stranded RNA molecule that is non-coding
- regulate the expression of genes, by a phenomenon known as RNAi
- have some role in changing the chromatin
Why must chromatin within centromeres be silents?
This is so centromeres can perform active/accurate cell division.
What is a centromere?
The centromere appears as a constricted region of a chromosome and plays a key role in helping the cell divide up its DNA during division (mitosis and meiosis). Specifically, it is the region where the cell’s spindle fibers attach.
What is the function of H3KIme3?
It is a repressor of lineage inappropriate gene. dsRNA nucleates complex that makes this.
What is the function of piRNA?
Transcribe from a DNA cluster made up of integrated disabled transposable elements in flies. Use argonaute PIWI which cleaves their RNA. It is important in regulating mRNA stability and enhancing protein synthesis.
What is the function of ncRNA? (novel cellular RNA)
It fine tunes physiological processes as organisms develop. It has strategies to combat viruses;
- make long RNA with repeating units that bind up microRNAs
- make circular RNA that soak up micromRNA which is important for defense
Females have Barr bodies that need to be inactivated. Where can you see this?
You can see the inactivation in calicocats - different coat colour information is from two different X chromosomes.
One X chromosome is inactive.
What is the function of XIST gene?
XIST locus encodes lncRNA (long non-coding RNA)
This binds to X chromosome regions and spreads along it, extinguishing gene expression.
How do lncRNAs regulate gene expression?
- TSIX and XIST are in female cells, inactivated X chromosomes is due to XIST expression or not.
- XIST coats X chromosome in cisXIST, recruiting complexes that modify chromatin. This condenses the chromosome making it inaccessible to transcription factors.
- XIST ad TSIX are mutually exclusive.
- XIST is a lncRNAs that coats X chromosomes are silences it.
- TSIX is a lncRNA that antagonizes XIST expression.
