RNAi

Question 1

Give an example of an sRNA.

Answer 1

oxyS sRNA binds flhA mRNA & stops its translation

flhA is transcriptional activator of formate metabolism.

Question 2

What are the actions of E.Coli RNAse III?

Answer 2

Promotes maturation of rRNAs, tRNAs, mRNAs.

Initiates mRNA degradation via sRNA.

Active as homodimer.

Question 3

Which RNAses are involved in miRNA?

Answer 3

Drosha (part of microprocessor complex with DGCR8) - cleaves pre-miRNA FROM pri-mRNA.

Dicer - cuts loop away from pre-miRNA to create miRNA:miRNA* duplex.

Question 4

what is argonaute?

Answer 4

a catalytic component of RISC.

Question 5

How do we know RNAi is significant with respect to transposons?

Answer 5

Mutations in RNAi can reactivate transposons, reversing transcriptional silencing.

Most transposons are located in heterochromatin and therefore silent (can cause mutational effects).

Question 6

What are the four main uses of knocking down genes using RNAi?

Answer 6

Study expression of TARGET genes and how reduction or absence of product effects phenotype.

ANTI-VIRAL drugs (block viral replication)

GENE therapies (knock down faulty gene causing disease phenotype)

ANTI-CANCER drugs (over-expression of genes is cause of many)

Question 7

What did the Herpes experiment show about siRNAs?

Answer 7

attractive candidates for active component of microbicide designed to prevent viral infection or transmission.

Question 8

How do we know RNAi is a common evolutionary strategy?

Answer 8

Many c elegant miRNAs have mammalian homologues.