Splicing & Processing of RNA

Question 1

RNA poly 1 transcribes what genes?

Answer 1

5.8S, 18S, & 28S rRNA genes

Question 2

What are 2 examples consistency sequences?

Answer 2

• transactivators
• invariant A

Question 3

What is RNA poly 2 transcribes what genes?

Answer 3

• all protein-coding genes
• snoRNA
• miRNA
• siRNA
• snRNA

Question 4

What are the 3 steps for mRNA processing?

Answer 4

1. Capping (5’ end)
2. Splicing (notice this is mRNA not rRNA)
3. Poly-A addition (3’ end)

Question 5

When does the methyl during 5’ capping get added to?

Answer 5

after synthesis of guanine (7-methylguanine)

Question 6

What happens if there is no 5’ cap?

Answer 6

CANNOT get mRNA to the ribosome

Question 7

What gene leads to deafness?

Answer 7

TECTA

Question 8

What is the human genome browser an example of?

Answer 8

If there are 2 splicing alternative, there will be 2 different primary transcripts that will have different exons.

Question 9

What invariant is important for splicing?

Answer 9

invariant A ( important for consistent sequence)

Question 10

What do introns turn into during mRNA splicing?

Answer 10

lariat structure

Question 11

What is the process of mRNA splicing?

Answer 11

1. Takes advantage of the 2OH on the invariant A nucleotide to attack the phosphodiester bond @ the 5’ end of an intron
2. The open OH on the exon closer to the 5’ end breaks phosphodiester bond between the 3’ end of intron and the exon
3. 5’ end of intron forms bond with 2’ OH of invariant A

Question 12

What are snRNPs made of?

Answer 12

polypeptides & RNA

Question 13

What are spliceosomes?

Answer 13

set of proteins important for making the lariat happen

Question 14

What are hnRNPs?

Answer 14

proteins that block formation of spiceosome & proteins that contact spliceosome

Question 15

In the case of igM, what are produced?

Answer 15

either secreted or membrane bound versions are produced depending on alternative splicing

Question 16

What helps to stimulate the formation of the spliceosome?

Answer 16

SE proteins

Question 17

What are the 4 RNA seqeunces?

Answer 17

• ESE (Exon Sequence Enhancer)
• ESS (Exon Sequence Silencers)
• ISE (Intron Sequence Enhancer)
• ISS (Intron Sequence Silencer)

Question 18

What can define what is an exon and what is an intron?

Answer 18

mutations & other things

Question 19

What is the regulatory sequence in a poly-A tail?

Answer 19

AAUAAA

Question 20

In what type of manner is a poly-A tail added?

Answer 20

template independent manner on 3’ end

Question 21

What is a Cleavage and polyadenylation specific factor (CPSF)?

Answer 21

• attaches to the RNA polymerase II
• binds to the Poly-A signal site of the emerging mRNA
• recruits polyA polymerase.

Question 22

When is RNA rapidly degraded?

Answer 22

if poly-A tails ARE NOT added

Question 23

What are snoRNAs?

Answer 23

• aka guide RNAs
• small nucleolar RNAs
• direct the position of the base modification for rRNAs

Question 24

What are the roles of the nucleolus, small nucleolar RNA, & small nuclear RNA?

Answer 24

• nucleolus: builds up ribosomes
• small nucleolar RNA: rRNA modifying enzyme
• small nuclear: RNA modifying enzymes

Question 25

What are snRNAs?

Answer 25

small nucelar RNAs

Question 26

In the TECTA article, what did the microsatellites show close to the DFNA8/DNFA12 locus?

Answer 26

significant multipoint lod scores close to marker D11S4107

Question 27

In the TECTA article, what included the last 2 bases of donor splice site?

Answer 27

deletion in the 5’ end of the intron 16

Question 28

What is the function of the ZP (zona pellucida) domain of the TECTA protein?

Answer 28

Most likely, to mediate polymerization with other proteins. Thus, if one allele encodes a defective copy of TECTA, the overall product of the polymerization process is likely to be defective.