Regulation Of Transcription 2

Question 1

What is rna editing

Answer 1

Alteration or modification of nucleotides in rna

Question 2

What rna goes through editing

Answer 2

Mrna tRNA and rRNA

Question 3

Which disease is caused by editing

Answer 3

Atherosclerosis

Question 4

How can editing affect the brain

Answer 4

High functioning things like depression

Question 5

How does editing allow parasites to be drug targets

Answer 5

Via U insertion in their mt

Question 6

Give 2 examples of methylation editing

Answer 6

M5cytosine - cytosine at n 5 is methylated irreversibly

M6adenine - methylated at 6’

Question 7

How does editing affect action of uridine which binds to adenine

Answer 7

It is converted to pseudouridine via an isomerisation reaction

Produces an extra H bond

Question 8

What is better about pseudouridine edited from uridine

Answer 8

It has extra h bond potential which increases rna stability

Question 9

Bases can be fully changed in identity aswell as altered. What are the 2 ways

Answer 9

A deamination to I (inosine)(recognised as G)

C to U deamination (loss of NH2)

Question 10

How can U insertion or U from c deamination affect mrna

Answer 10

Can cause introduction of a start AUG codon or a stop UAA/UAG codon

Question 11

How does editing such as change in bases affect splicing

Answer 11

Can change splice sites

Question 12

Can editing cause change in AA sequence

Answer 12

Yes Eg via insertion/deletion or alteration via deamination

Question 13

Does M6A methylation affect base pairing of A with U

Answer 13

No

Question 14

How can m6a affect rna

Answer 14

Methylation can either stimulate protein binding. Proteins which improve rna stability

Or

It can block then causing instability and degradation

Question 15

Which eraser of the m6a is involved in obesity

Answer 15

FTP

Question 16

Other than protein binding what does m6a affect

Answer 16

Splicing, export and translation

Question 17

How does cytidine deamination to U affect apo B gene in intestines

Answer 17

In intestines the c is deaminated to U in the apoB gene introducing a new stop codon. The protein is much shorter forming apob48 and without an LDL receptor

Question 18

Does cytidine deamination into U occur in liver apoB gene

Answer 18

No. There is no stop codon and so long protein apoB 100 is produced with an LDL receptor intact

Question 19

Which enzyme deaminates A to I

Answer 19

Adar 2

Question 20

How has A deamination to I via adar 2 affected transmission of glutamate Nt across synapse

Answer 20

Changed amino acid in transporter from Q glutamine to R arginine. This transporter is now not permeable to calcium = no transmission

Question 21

How is ribose modified in trna, snrna and rRNA

Answer 21

2’ O methylation of ribose

Question 22

How does ribose 2’ o methylation affect things in trna rRNA and snrna

Answer 22

Changes stability by blocking nucleases

Also changes protein binding

Question 23

What happens to yeast if there’s no rRNA 2’ o methylation on ribose

Answer 23

They die

Question 24

What Happens to yeast if the pseudouridine from isomerisation of uridine in rRNA is removed

Answer 24

Defect in translation as it needs rRNA stability

Question 25

Which enzyme is mutated which modifies rRNA in dyskeratosis congenita

Answer 25

Pseudouridine synthase

Question 26

Does editing also occur on non coding rna

Answer 26

Yes Eg sn rna 2’ o methylation

Question 27

Explain the structure of nuclear pores

Answer 27

Nucleoplasm and cytoplasm are separated by the outer and inner nuclear membrane There is a nuclear basket and on the cytoplasmic side there are long cytoplasmic filaments

Question 28

What 2 things are needed for exportation

Answer 28

Export factors and export adapters

Question 29

What do export adapters do

Answer 29

Couple processes like capping, poly A which have export factors with mrna to export receptors/factors

Question 30

What is an important thing in exportation for energy

Answer 30

Ran gtp

Question 31

Which export factors carries trna

Answer 31

Exp-t

Question 32

Which export factor carries mirna

Answer 32

Exp-5

Question 33

Which rnas need export adapters to attach to them and connect them to export receptors

Answer 33

Snrna,mrna and rRNA

Question 34

Which export adapter is the main one in mrna exportation

Answer 34

ALY/yra1

Question 35

What are the 2 human export factors for mrna (attach to ALY/yra1)

Answer 35

TAP and p15

Question 36

What is rna localisation described as

Answer 36

Asymmetric

Question 37

What is importance of rna localisation being asymmetrical

Answer 37

Localised protein synthesis Generates cell polarity in development Prevents expression of genes I. Wrong place

Question 38

Give an example of cell polarity via asymmetrical mrna localisation

Answer 38

Bcd bicoid mrna localised on edge of oocyte to form the APVD axis When proteins are translated they form a gradient forming the axis

Question 39

Give an example of localised translation of mrna = prevents expression In wrong place

Answer 39

NTs mrna is translated at the synapse after travelling down dendrites

Question 40

Which 2 modes of transport do mrna localise through

Answer 40

Diffusion and active transport

Question 41

Which proteins hold and localise mrna after diffusion localisation

Answer 41

Anchor proteins

Question 42

Give an example of active transport localisation

Answer 42

Mrna moves down dendrite via AT anchored to the cytoskeleton

Question 43

What state is mrna in until right localisation

Answer 43

Inactive state so no translation occurs