RNAi and CRISPR Flashcards
Define RNAi.
Gene silencing by double-stranded RNA.
What type of molecule does the cleaving of dsRNA into fragments produce?
Small interfering RNAs (siRNAs).
What enzyme makes siRNA single-stranded?
Ago2.
The dsRNA associates with a RISC. True or false?
False.
What does RISC stand for?
RNA-induced silencing complex.
What molecule activates the RISC?
Single-stranded siRNA.
When does RNAi lead to full mRNA degradation?
When there is perfect complementarity between siRNA and target mRNA.
What happens if the siRNA is not a perfect complement to the target mRNA?
Translation inhibition - RISC stays bound to mRNA.
What are the three functions of Ago2 in RNAi?
- Unwind double-stranded siRNA.
- Transport ss-siRNA to RISC.
- Assist RISC in mRNA degradation.
What is the name of the RNase that produces the siRNAs?
Dicer.
What are two applications of RNAi?
- Knockdown studies.
- Inhibition of protein synthesis in cancer cells.
The bacterial system where short RNA transcripts hydrolyse complementary DNA is called…
CRISPR-Cas.
What does CRISPR stand for?
Clustered Regularly Interspaced Short Palindromic Repeats.
Define CRISPR-Cas9.
A genome-editing system using Cas9 protein.
What does gRNA stand for?
Guide RNA.
Cas9 is complementary to the target gene. True or false?
False.
What part of gRNA recognises the target gene?
5’ guide sequence.
How long is the gRNA guide sequence?
20 bp.
What part of the gRNA binds to Cas9?
3’ gRNA scaffold.
Cas9 is a DNA-guided endonuclease. True or false?
False.
Cas9 cuts both strands, called a…
Double-stranded break (DSB).
When Cas9 complexes with gRNA, the molecule is referred to as a…
Ribonucleoprotein.
What does PAM sequence stand for?
Protospacer Adjacent Motif sequence.
What is the motif of PAM?
5’-NGG-3’
