Exam 1 - mRNA Processing

Question 1

what is are the three most important structures in a mRNA

Answer 1

1 - 5’ cap
2 - splicing proteins (internal)
3 - 3’ (poly a tail)

Question 2

Describe the 5’ cap and what it does

Answer 2

upside down and backwards guanine with methyl group

1 - resistant to digestion nucleus
2 - Has CAP binding proteins that:
a) initiate splicing and adding a poly a tail
b) direct mature RNA though nuclear pore
c) recruit translation IF (eIF’s)

Question 3

What are the 4 splicing introns

Answer 3

1 - Group 1 introns
2 - Group 2 introns
3 - spiceosomal introns
4 - tRNA/archaeal introns

Question 4

Group 1 introns

Answer 4

-found in prokaryotes, eukaryotes, and organelles
REMOVED BY:
- found in rRNA genes in eukaryotes
- self catalyzed
- linear or circular intron

Question 5

Group 2 introns

Answer 5

• found in prokaryotes, eukaryotes, and organelles
  REMOVED BY:
• self catalyzed
• some require protein helper
• lasso structure

Question 6

Splicesomes

Answer 6

• EUKARYOTES ONLY
  REMOVED BY:
  -protein mediated (splicesome)
• Lasso structure

Question 7

Spliceosome is a mixture of

Answer 7

RNA and protein

Question 8

tRNA/ archaeal intron

Answer 8

-found in eukaryotes and organelles and archaebacteria
REMOVED BY:
- protein mediated
a) endonuclease - removes
b) ligase: reconnects

Question 9

What is alternative splicing

Answer 9

• a way to increase genetic diversity
• does not change DNA sequence

Question 10

what is polyadenylation and function

Answer 10

200-250 adenines at the 3’ tail of RNA

-defines exact 3’end of the RNA
- has a PABP that is resistant to digestion of the nucleus and binds to eIF to circularize the mRNA and start translation

Question 11

CPSF to ___________ and
CstF downstream to _________

Answer 11

1 - polyadenylation signal site
2 - DSE site

Question 12

what does PAP and PABP do

Answer 12

PAP = adds a tail
PABP = coats the tail

Question 13

Noncoding RNA makes up ____ of all RNA

Answer 13

98%

Question 14

what is the only coding RNA

Answer 14

mRNA - messenger RNA codes for proteins

Question 15

snRNA
Name:
Transcribed:
Size:
Role:

Answer 15

• small nuclear RNA
  -RNA pol 1 and 2
• mid range
• part of splicosome

Question 16

snoRNA
Name:
Transcribed:
Size:
Role:

Answer 16

• small nucleolar RNA
  -RNA pol 2
• mid range
• chemical modification of nucleic acid (tRNA,rRNA,snRNA)

Question 17

miRNA
Name:
Transcribed:
Size:
Role:

Answer 17

-micro RNA
-RNA pol 2
-small
-inhibit translation hairpin with a bulge

Question 18

siRNA
Name:
Transcribed:
Size:
Role:

Answer 18

-small interfering RNA
- small
- block translation by degrading RNA
- block transcription by promoting heterochromatin
- no bulge and no hairpin

Question 19

piRNA
Name:
Transcribed:
Size:
Role:

Answer 19

-PIWI interacting RNA
-RNA pol 2
- small
- silence transposons by methylating DNA

Question 20

lncRNA
Name:
Transcribed:
Size:
Role:

Answer 20

-long noncoding RNA
- RNA pol 2
- SIGNALL
- xist = coats x chromo to inactivate it
- DECOY
- GAS5 = binds to receptor to prevent signal cascade
-GUIDE
- HOTAIR = localizes HMT
-SCAFFOLD
- physically connects proteins to activated transcription
-ceRNA NETWORKS
- miRNAregualtion

Question 21

rRNA
Name:
Transcribed:
Size:
Role:

Answer 21

-ribosomal RNA
- RNA pol 1 and 2
- mid range to long
- component of ribosome
- large and small subunits
- 3 binding sites for tRNA
- A.P.E

Question 22

tRNA
Name:
Transcribed:
Size:
Role:

Answer 22

-transfer RNA
-RNA pol 3
- mid range
- deliver amino acids to growing peptide chain