L08

Question 1

what steps are involved in polyadenylation

Answer 1

1. endonuclease cleavage
2. Addition of As by polyA polymerase

Question 2

what is the conserved sequence that allows endonuclease cleavage?

Answer 2

AAUAAA

Question 3

how far is the conserved AAUAAA sequence from the poly(A) site

Answer 3

10-35 nucleotides upstream of the poly(A) site

Question 4

where is the G/U rich tract located in relation to the poly(A) site?

Answer 4

just downstream of the poly(A) site

Question 5

what is USE

Answer 5

U rich element upstream the poly(A) site

Question 6

what proteins are required for polyadenylation

Answer 6

1. Cleavage and polyadenylation specificity factor (CPSF)
2. Cleavage stimulatory factor (CstF)
3. Poly(A) polymerase

Question 7

what does CPSE bind to

Answer 7

AAUAAA

Question 8

what does CstF bind

Answer 8

G/U rich tract

Question 9

what are the features of the poly(A) tail.

Answer 9

1. All mRNAs has 3’ poly(A) tail (a few exceptions e.g. histones)
2. Approx 250 nucleotides long
3. Bound by poly A-binding protein
4. Enhances export of RNA
5. Stabilises the 3’ end of the mRNA
6. Enhances translation of mRNA

Question 10

histone mRNAs contain 3’ poly(A) tail

Answer 10

False

Question 11

the poly(A) tail is a protein binding element

Answer 11

true

Question 12

what is RNA editing

Answer 12

nucleotide alterations which result in different or additional nucleotides in the mature RNA

Question 13

in what classes of RNA does editing happen

Answer 13

mRNA, tRNA, ribosomal RNA (rRNA)

Question 14

what are the 2 classes of RNA editing

Answer 14

1. insertion/deletion
2. modification (e.g. A to I, C to U, U to C)

Question 15

what percentage of RNA undergoes editing

Answer 15

20

Question 16

what areas of medicine are impacted by RNA editing

Answer 16

1. disease
2. brain function
3. development
4. parasites

Question 17

what disease is associated with RNA editing (A changed into I)

Answer 17

Atherosclerosis

Question 18

what areas of brain function is affected by RNA editing

Answer 18

higher brain function and depression

Question 19

what areas of development in drosophila is impacted by RNA editing

Answer 19

neurological development

Question 20

which parasite undergoes mitochondrial RNA editing which can act as a drug target.

Answer 20

Trypanosoma

Question 21

what are the 2 types of base modification

Answer 21

1. marked nucleotide (methylation)
2. Altered identity

Question 22

in which position does methylation happen in Adenine

Answer 22

6

Question 23

which nucleotide methylation is reversable

Answer 23

Adenine

Question 24

in which position is cytosine methylated

Answer 24

5

Question 25

what are the 2 types of altered identity modifications

Answer 25

A to I C to U

Question 26

how does altered identity modification take place

Answer 26

enzymatic deamination

Question 27

what is inosine recognized as?

Answer 27

guanine

Question 28

which enzyme carries out the editing of ApoB-100 producing ApoB-48 in the intestine

Answer 28

APOBEC-1

Question 29

ApoB-100 and ApoB-48 have the same function

Answer 29

False

Question 30

ApoB-100 is a major component of very low density lipoproteins linked to atherosclerosis

Answer 30

True

Question 31

what are the edits made in the intestine to ApoB

Answer 31

CAA to UAA (a stop codon)

Question 32

what does ApoB-100 have that ApoB-48 does not

Answer 32

LDL-receptor binding

Question 33

what type of editing happen in the L-glutamate receptor?

Answer 33

altered identity (A to I)

Question 34

what protein does the unedited version of L-glutamate have

Answer 34

Q

Question 35

what protein does the edited version of L-glutamate have

Answer 35

R

Question 36

what results in the editing of L-glutamate

Answer 36

decrease in Ca2+ permeability of channels containing the ‘R’ version (helps avoid overstimulation and excitotoxicity

Question 37

which gene carries out the editing of L-glutamate

Answer 37

ADAR2 (adenosine deaminase acting on RNA)

Question 38

what method of transport is required to export RNA from the nuclous to the cytoplasm

Answer 38

active transport

Question 39

different factors are involved in exporting RNA based on classes

Answer 39

True

Question 40

why is mRNA localized

Answer 40

1. Localized protein synthesis 2. Prevents expression in the wrong place 3. Promotes efficiency of subsequent protein targeting 4. Local control of translation e.g. synapses

Question 41

how are mRNAs localized in diffusion based localization

Answer 41

mRNAs freely diffuse in the cytoplasm and are locally entrapped by anchor proteins

Question 42

how are mRNAs localized in active transport based-localization

Answer 42

1. mRNA recognized by specific trans-acting factors in the nucleus 2. cytoplasmic factors ensure transport along a polarized cytoskeleton