L10

Question 1

What is the range of hlf-life for RNA’s

Answer 1

Minutes to days

Question 2

Why do we need to remove DNA?

Answer 2

Damaged DNA
Incorrectly transcribed/processed mRNA
Control gene expression

Question 3

What are the 2 ways mRNA loop can be broken?

Answer 3

Loss of the cap OR by progressive loss of the poly (A). tail.

Question 4

What form of decay do most RNA go through?

Answer 4

Deadenylation-dependent decay

Question 5

What occurs in deadenylation-dependent decay?

Answer 5

Removal of poly(A) tail.

Question 6

What enzymes are involved in the deadenylation-dependent decay?

Answer 6

CCR4-NOT (complex)

Question 7

What is the exosome?

Answer 7

A complex of nucleases and other enzymes

Question 8

What does the exosome do to the RNA?

Answer 8

Unwinds the 3’ end

Question 9

What things are involved in the decapping of mRNA?

Answer 9

DCP1,DCP2 complex and XRN1

Question 10

What are the 2 enzymes that decay most the RNA

Answer 10

Exosome - 3’ to 5’
XRN1 - 5’ to 3’

Question 11

What do endonucleases do?

Answer 11

Cut RNA through the middle

Question 12

List three endonucleases

Answer 12

Argonaute, Swt1, Smg6

Question 13

What is the general method for RNA degradation?

Answer 13

Removal of the cap and the poly(A) tail

Question 14

What enzymes are involved in deanylation-dependent decay?

Answer 14

Deadenylysases (CCR4 NOT)

Question 15

What enzymes are involved in 3’ to 5’ degradation?

Answer 15

Exosome

Question 16

What enzymes are involved in decapping of mRNA?

Answer 16

DCP1&2

Question 17

What enzymes are involved in 5’ to 3’ degradation?

Answer 17

XRN1

Question 18

Is the exosome involved in RNA turnover and processing?

Answer 18

Yes

Question 19

What subunits engage in nuclease activities

Answer 19

RRP6 - only in the nuclease
RRP44 - KEY PROTEIN IN FOR DEG. in cytoplasm

Question 20

What other things to the subnits fx in?

Answer 20

RNA binding and unwinding

Question 21

Is XRN1 involved in RNA turnover and processing?

Answer 21

Yes

Question 22

List things XRN1 is involved in

Answer 22

RNA turnover and processing
Transcription termination
fxs after decapping of the mRNA

Question 23

What causes deadenylation-dep. decay?

Answer 23

AU rich element/ARE
Nonsense codon: stop codon in the wrong place ?

Question 24

What could cause a nonsense mutation?

Answer 24

Transcription, spilcing, editing, polyadenylation, mutations

Question 25

What occurs in nonsense Mediated Decay

Answer 25

Mistakes (PTC - premature stop codons) in the RNA are detected, RNA is targeted for degradation

Question 26

What portion of inherited disorders are caused by nonsense or frameshift mutations that can introduce PTC

Answer 26

1/3

Question 27

At what distance from the original stop codon is a PTC (premature stop codon) treated normally

Answer 27

Less than or equal to 55 nucleotides

Question 28

At what distance from the original stop codon is a PTC (premature stop codon) treated as a potential NMD (nonsense mediated decay)

Answer 28

Greater than 55 nucleotides

Question 29

When are the EJC (exon junction complexes) removed from the mRNA?

Answer 29

First round of translation

Question 30

What removes the EJC (exon junction complexes) from the mRNA?

Answer 30

Ribosome

Question 31

When is the EJC not removed?

Answer 31

When the mRNA leaves the ribosome too soon

Question 32

What proteins interact with the RNA degradation machine if there are remaining EJCs?

Answer 32

UPF proteins

Question 33

What is RNA surveillance?

Answer 33

Ensuring that the RNA is working properly

Question 34

What is RNAi?

Answer 34

RNA interference

Question 35

What is siRNA?

Answer 35

Small inhibitory RNA

Question 36

What is miRNA?

Answer 36

Micro RNA

Question 37

What is RISC?

Answer 37

RNA induced silencing complex

Question 38

How long are miRNAs?

Answer 38

21-23 nucletide RNAs

Question 39

How long are siRNAs?

Answer 39

21-23 nucleotide RNAs

Question 40

Are miRNA perfectly complimentary to target RNA

Answer 40

No

Question 41

Are siRNA perfectly complimentary to target RNA

Answer 41

Yes

Question 42

Which is involved in viral defence mechanism? siRNA or miRNA

Answer 42

siRNA

Question 43

Which is involved in key gene regulatory mechanism in the cell? siRNA or miRNA

Answer 43

miRNA