Lecture 21

Question 1

Tc1 in C elegans

Answer 1

Transposon, independent, can jump by itself, has RT and flanking regions

Question 2

RNAi silencing pathway of the gene inhibiting Tc1 transposition

Answer 2

Typically: short RNA sequences are shipped to teh cytoplasm to meet dicer, a protein that will cut the strands into the fragment it wants, goes to RISC complex (RNAi induced silencing complex), isolates one of the small strands and then this floats around targetting and degrading the mRNAs it binds to or repressing its translation
Same can be done with transposons, so the short RNA sequences will be that of transposons, leading to inhibition of transposon transcript translation
If any step is altered, we will get excessive jumping, unblocking the jump, and thats what happened in C elegans, these r the genes they were disturbing

Question 3

How do we get the ds RNA in RNAi if RNA isnt ds

Answer 3

Happens when the transposon is entirely within the frame of transcription, the LTRs can base pair with each other, or wtv the flanking regions are, and these form the hairpin ds structure recognized by dicer

Question 4

Similarities between siRNAs and piRNAs

Answer 4

Both start as small RNA, they interact with a protein complex that will help it degrade complementary RNA transcripts

Question 5

Differences between siRNAs and piRNAs

Answer 5

Pi dont start ds, si do
Pi starts as part of a longer “mother strand” from the pi-cluster, the graveyard