Lectures 7-8: Post-transcriptional control of gene expression 1

Question 1

what does LUCA stand for?

Answer 1

last universal common ancestor

Question 2

approx how many amino acids long is the Poly A tail added to eukaryotic mRNA?

Answer 2

250 residues

Question 3

the m7G cap facilitates 4 things to do with mRNA. name them

Answer 3

protection, splicing, translation, export

Question 4

true or false, m7G cap is encoded in the genome?

Answer 4

false

Question 5

true or false, the m7G cap is a protein binding element?

Answer 5

true

Question 6

in mammals, which are longer in nucleotide number, introns or exons?

Answer 6

introns are longer

Question 7

which gene, linked to Duchenne muscular dystrophy, contains an intron which is 210,000 nucleotides in length?

Answer 7

Dystrophin

Question 8

what does the spliceosome catalyse the removal of?

Answer 8

introns

Question 9

true or false, the spliceosome does not require ATP?

Answer 9

false, it does

Question 10

the spliceosome contains U1, U2, U4, U5, U6 which help to catalyse splicing. What are these known as?

Answer 10

snRNPs - small nuclear ribonucleoprotein particles

Question 11

which splice site does the snRNP U1 base-pair with in the intron? 5’ or 3’

Answer 11

5’

Question 12

in snRNPs, the Sm ring binding site consensus sequence is what?

Answer 12

A/G - GAUUUUUG- A/G

Question 13

anti - Sm ring antibodies are rare unless you have which autoimmune disease?

what are some common symptoms of this disease?

Answer 13

systemic lupus erythematosus (SLE)

butterfly rash on face, photosensitivity, fatigue, mouth ulcers, muscle aches, arthritis, poor circulation, inflammation of the pleura and pericardium

Question 14

How many conserved sequences are involved
in splicing

Answer 14

4

Question 15

Splicing is an RNA catalysed event, true or false?

Answer 15

true

Question 16

name 3 diseases which are characterised by mutations causing defects in splicing

Answer 16

spinal muscular atrophy

retinitis pigmentosa

myotonic dystrophy (muscle wasting)

Question 17

polyadenylation involves cleavage via which enzymes?

it then involves the addition of which nucleotides by polyA polymerase?

Answer 17

endonuclease

A

Question 18

how many nucleotides upstream of the polyA site is the conserved AAUAAA sequence found? (hint - answer is a range)

Answer 18

10-35

Question 19

10-35 nucleotides upstream of the polyA site is which conserved sequence?

Answer 19

AAUAAA

Question 20

upstream of the poly A site is a ……. rich element?

Answer 20

U

Question 21

just downstream of the polyA site is a ……. and ……… rich tract

Answer 21

G and U

Question 22

which protein binds the AAUAAA conserved sequence, located upstream of the ployA site?

Answer 22

CPSF

Question 23

which protein binds the G/U tract, downstream of the polyA site?

Answer 23

CstF

Question 24

all mRNAs have a 3’ polyA tail except…..

Answer 24

histones

Question 25

the polyA tail enhances RNA export as well as RNA ........ and ..........

Answer 25

protection and translation

Question 26

what are the 2 classes of RNA editing? what does RNA editing alter the sequence of in mature RNA?

Answer 26

insertion/deletion modification alters nucleotide sequence

Question 27

what letter can G be altered to in enzymatic deamination/base modification? (it will still pair with C)

Answer 27

the letter I

Question 28

mRNA edition can create new .............. by nucleotide INSERTION?

Answer 28

open reading frames

Question 29

A to I editing occurs in which site of glutamate receptors?

Answer 29

Q/R site

Question 30

the editing of glutamate receptors causes a decrease in Ca2+ permeability of channels containing which version of the receptor?

Answer 30

R version

Question 31

the editing of glutamate receptors is carried out by which adenosine deaminase acting on RNA? what does this editing of glutamate receptors cause to the body?

Answer 31

ADAR2 neurodegeneration in hippocampus, post-natal death, seizures

Question 32

active transport of mRNA from nucleus to cytoplasm requires active transport because the nuclear pore is......... but RNA is ........

Answer 32

nuclear pore is hydrophobic but RNA is hydrophillic

Question 33

localisation of mRNA must take place before what?

Answer 33

translation

Question 34

many RNAs are localised............. which is essential for cell differentiation and function

Answer 34

asymmetrically

Question 35

what is the order of events which happen post translationally? polyadenyation mRNA localisation capping editing splicing

Answer 35

- Capping - Splicing - Polyadenylation - Editing - mRNA localisation