Post Transcriptional Gene Control

Question 1

What protective modifications are added to Pre-mRNA before being exported to the nucleus to be translated?

Answer 1

• Capped (5’ Cap)
• Splicing (Splicing of Introns)
• Polyadentlyated (Poly-A Tail_
• Associated with the RNPs in the nucleus

Question 2

Describe the act of splicing in pre-mRNA.

Answer 2

A large ribonucleoprotien splice some complex catalyzes the joining ig two exons and the removal of introns.

Question 3

What is responsible for correctly specifying splice sites?

Answer 3

A network of interactions between SR proteins, snRNPs, and spiffy factors to form a cross-section recognition complex.

Question 4

List the order in which pre-mRNA is processed in eukaryotes after transcription.

Answer 4

1. 5’ Capping
2. Cleavage at the poly(A) site
3. Polyadenylation
4. RNA splicing

Question 5

List two alternative methods of splicing of mRNA

Answer 5

1. Sex determination in Drosphilia
2. Alternative splicing in neurone of vertebrates

Question 6

Alternative promoters, alternative splicing, and alternative cleavage at different poly(A) sites yield ______ mRNA from the same gene in different cell types or developmental stages.

Answer 6

Different

Question 7

_______ are binding to specific sequences near splice sites and regulate alternative splicing.

Answer 7

RNA-binding proteins

Question 8

Sex-lethal, Tra and Dsx regulate ________ in flies (drosophila).

Answer 8

Sexual differentiation

Question 9

What is Sxl? Is it a repressor or activator of splicing?

Answer 9

RNA binding proteins that acts as a repressor of splicing.

Question 10

What is Tra? Is it a repressor or activator of splicing?

Answer 10

RNA binding proton that acts as an activator of splicing.

Question 11

What is the role of Dsx in Drosphilia?

Answer 11

Transcription activator/repressor.

Question 12

Sxl controls its own splicing to produce exons ______.

Answer 12

2,4 mRNA.

Question 13

Males do not include the _____ protein.

Answer 13

Sxl

Question 14

In males, in the absence of Sxl, the transcripts spliced into exon 2,3,4 mRNA. Where is the stop codon found?

Answer 14

Exon 3 of Sxl

Question 15

Male or female? sxl - 2,4

Answer 15

Female

Question 16

Male or female? sxl - 2,3,4

Answer 16

Male -> NOT EXPRESSED

Question 17

Male or female? tra - 1,3

Answer 17

Female

Question 18

Male or female? tra -1,2,3

Answer 18

Male - NOT EXPRESSED

Question 19

Sxl regulates the splicing of the transcript STOP codon in exon ____ of Tra.

Answer 19

Exon 2

Question 20

Tra regulates __________ and cleavage of Dsx into male and female 2. ________.

Answer 20

1. Alternate splicing
2. Isoforms

Question 21

Male or female? Dsx - 3,4

Answer 21

Female

Question 22

Male or female? Dsx -3,5

Answer 22

Male

Question 23

Dsx is a ________ binding to DNA with the same DNA binding site in both male and female isoforms.

Answer 23

Transcription factor

Question 24

The alternative spliced female isofrom of Dsx contains a transcriptional ___________ (activation/repression) domain.

Answer 24

Activation

Question 25

The alternative spliced male isofrom of Dsx contains a transcriptional ___________ (activation/repression) domain.

Answer 25

Repression

Question 26

Slx acts as an intron splicing ________ (or inhibitor).

Answer 26

Silencer

Question 27

Tra acts as an intron splicing _______.

Answer 27

Activator

Question 28

What is the role of alternative splicing in neurons?

Answer 28

The perception of sounds and neuron connectivity.

Question 29

miRNA and siRNA regulate the __________ and the ________ of mRNA.

Answer 29

Stability and translation.

Question 30

siRNA degrade _____ RNA and RNA produced by _________.

Answer 30

Viral, transposons

Question 31

miRNA IMPERFECTLY bind to the target mRNA. The binding is usually within the 3'-UTR. The imperfect binding leads to _____________.

Answer 31

Repression of translation.

Question 32

How is siRNA produced?

Answer 32

From cleavage of double stranded RNA

Question 33

siRNA are produced from the cleavage of _________ DNA

Answer 33

Double stranded

Question 34

siRNA bind PERFECTLY to the target RNA and cause what?

Answer 34

Rapid degradation by a mechanism called RNA interference. RNA interference controls multiple processes.

Question 35

Abnormalities in particular miRNA levels play a role in the development of diseases including ______.

Answer 35

Cancer

Question 36

Explain the function of Drosha.

Answer 36

Remove the hairpins in double stranded RNA.

Question 37

Describe the function of Exportin.

Answer 37

Transporting the processes miRNA to the cytoplasm.

Question 38

Describe the function of DICER.

Answer 38

Cuts the double stranded RNA into small pieces.

Question 39

Describe the function of Argonaut (RISC).

Answer 39

Removes one of the strands of the double stranded RNA and targets the mi

Question 40

Describe the four steps associated with RNA interference.

Answer 40

1. Double stranded RNA is cleaved to small fragments by DICER. 2. Small double stranded RNAs bind to RISC and form an inactive complex. 3. Argonaut in RISC is an RNA helicase. It unwinds the double stranded RNA and an active RISC* is formed. 4. RISC*, guided by single-stranded siRNA, cleaves target mRNA ("SLICER" activity by Argonaut)

Question 41

What happens with the amplification of RNAi?