post transcriptional gene control

Question 1

what are two examples of alternative splicing of mRNA?

Answer 1

• sex determination in drosphila
• alternative splicing in neurone of vertabrates

Question 2

what are two types of alternative splicing of mRNA?

Answer 2

• sex determination in drosophila
• alternative splicing in neurone of vertebrates

Question 3

what do alternative promoters, alternative splicing and alternative at different pol(A) sites yield?

Answer 3

yield different mRNAs from the same gene in different cell types or at different developmental stages

Question 4

RNA-binding proteins bind to specific sequences near _____ and regulate ______.

Answer 4

splice sites, alternative splicing

Question 5

what is Sxl? what does it act as?

Answer 5

an RNA binding protein.
acts as a repressor/inhibitor of splicing

Question 6

what is Tra? what does it act as?

Answer 6

RNA binding protein
acts as an activator of splicing

Question 7

what is Dsx?

Answer 7

a transcriptional activator/repressor

Question 8

the female isoform of Dsx contains a transcriptional ______ domain.

Answer 8

activation

Question 9

the male isoform of Dsx contains a transcriptional ______ domain.

Answer 9

repression

Question 10

what is the role of alternative splicing in neurons?

Answer 10

• perception of sounds
• neuron connectivity

Question 11

what do miRNA and siRNA regulate?

Answer 11

the stability and the translation of mRNAs

Question 12

what does miRNA imperfectly bind to?
where does it bind?
what does this binding lead to?

Answer 12

binds the target mRNA.
binding is usually within the 3’-UTR.
imperfect binding leads to repression of translation

Question 13

how are siRNA produced?

Answer 13

from cleavage of double stranded RNA

Question 14

does miRNA bind perfectly or imperfectly?

Answer 14

imperfectly

Question 15

does siRNA bind perfectly or imperfectly?

Answer 15

perfectly

Question 16

what does siRNA perfectly bind to?
what does this cause?

Answer 16

binds to the target RNA
causes its rapid degradation by a mechanism called RNA interference

Question 17

what is the function of miRNAs important for?

Answer 17

limb development

Question 18

explain the formation of dsRNA

Answer 18

1. Drosha: removal of hairpins in dsRNA (cuts of 3’ and 5’ ends)
2. Exportin: transporting the processed miRNA to the cytoplasm
3. DICER: cuts the dsRNA into small pieces
4. Argonaut (RISC): removes one of the strands of the dsRNA. keeps the strand that is complementary to the RNA of interest

Question 19

explain RNA interference

Answer 19

1. dsRNA is cleaved to small RNA fragments by a dsRNA-endonuclease called DICER
   2.