Lecture 10

Question 1

hnRNAs

Answer 1

heterogenous nuclear RNAs in nucleus, RNA processing intermediates

Question 2

mRNA

Answer 2

fully processed messenger RNA

Question 3

pre-mRNA

Answer 3

no cap/AAAtail, includes introns

Question 4

snRNA

Answer 4

5 small nuclear RNAs that help remove introns in splicing of pre-mRNA

Question 5

pre-tRNA

Answer 5

precursor tRNA with additional bases at 5’ and 3’ ends

Question 6

pre-rRNA

Answer 6

unmodified, uncut precursor rRNA

Question 7

snoRNA

Answer 7

small nucleolar RNA base pair with pre-rRNA aiding in its modification and maturation

Question 8

siRNA

Answer 8

100% complementary to mRNA involved in RNA cleavage

Question 9

miRNA

Answer 9

not 100% complementary, prevents translation

Question 10

Splicing was discovered in what?

Answer 10

adenoviruses

Question 11

introns

Answer 11

size can vary but does not affect rate of splicing

Question 12

5’ splice site

Answer 12

GU

Question 13

3’ splice site

Answer 13

AG

Question 14

branch point

Answer 14

A

Question 15

polypyrimidine tract

Answer 15

CU repeats

Question 16

invariant bases

Answer 16

5’ and 3’ splice sites (GU-AG) and branch point A

Question 17

what reactions does splicing occur

Answer 17

2 sequential transesterification reactions

Question 18

products of splicing

Answer 18

spliced exons, lariat intron that includes branch point A

Question 19

snRNP

Answer 19

small nuclear ribonucleoproteins consisting of snRNA and associated proteins

Question 20

5 U-rich snRNA

Answer 20

U1, U2, U4, U5, U6

Question 21

debranching enzyme

Answer 21

nuclear exoribonuclease converts lariat intron to linear intron

Question 22

what are the two poly-A signals

Answer 22

Upstream from poly(A) site = AU

Downstream from poly(A) site =G/U

Question 23

What helps stabilize complex of polyadenylation complex?

Answer 23

cleavage factors

Question 24

PAP Poly(A) Polymerase

Answer 24

binds to Poly A site and cleaves it

Question 25

where does ALL mRNA modification occur?

Answer 25

in nucleus

Question 26

3 types of exonuclease degradation of RNA

Answer 26

deadenylation dependent decay of mRNA, deadenylation INdependent decay of mRNA, No-Go

Question 27

mRNA exporter

Answer 27

binds to RNA and proteins and associates with proteins in the nuclear pore complex

Question 28

What interacts with the UPSTREAM Poly(A) signals

Answer 28

Cleavage and Polyadenylation Specificity Factor (CPSF)

Question 29

What interacts with the DOWNSTREAM Poly(A) signals

Answer 29

Cleavage Stimulatory Factor (CStF)

Question 30

when are mRNAs marked for degradation

Answer 30

when they are not translated

Question 31

Where does deadenylation-dependent mRNA degradation occur?

Answer 31

P-bodies - sites in the cell where there are NO ribosomes present but high concentration of mRNA decay enzymes

Question 32

Deadenylase complex

Answer 32

breaks off interactions between PABPC and eIF4E and removes A's from tail

Question 33

decapping enzyme complex

Answer 33

removes 5' cap

Question 34

exonuclease

Answer 34

chops up RNA

Question 35

mTOR

Answer 35

a protein kinase that responds to multiple signals including nutritional

Question 36

how does the mTOR pathway get triggered

Answer 36

growth factor binds to cell which activates mTOR to grow = decreases autophagy

Question 37

What are the dsRNA-binding proteins involved in miRNA processing

Answer 37

DGCR8 (in nucleus) and TRBP (in cytosol)

Question 38

Where is Drosha and Pasha and what is Drosha?

Answer 38

In the nucleus, Drosha is an endoribonuclease

Question 39

What does Dicer do?

Answer 39

Further cuts pre-miRNA

Question 40

Function of RISC

Answer 40

binds to one of the dsRNA strands to prevent translation

Question 41

What is mTORC?

Answer 41

mTOR bound to a protein

Question 42

Active mTORC

Answer 42

protein synthesis, activates polymerases, decreases autophagy

Question 43

Inactive mTORC

Answer 43

low levels of nutrients and energy, stress responses

Question 44

Iron response element binding protein (IRE-BP)

Answer 44

activated = hinders translation of ferritin mRNA to control concentrations of iron

Question 45

NoGo decay

Answer 45

mRNA contains a damaged base that causes a strong structure within mRNA (i.e.: hairpin loop) = cannot undergo translation

Question 46

where does rRNA get processed?

Answer 46

nucleolus

Question 47

rRNA processing purpose?

Answer 47

cut rRNA to correct size snoRNA via exonuclease due to base pairing with rRNA

Question 48

what is involved in rDNA splicing?

Answer 48

U3