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Question 1

how can cells respond quickly to external stimuli

Answer 1

to preposition mRNA so that it can be rapidly tranlsted

Question 2

mRNA in egg cells

Answer 2

prepositions but not translation until after fertilization

Question 3

mRNA in a fruit fly (drosophilia)

Answer 3

bicoid mRNA in fruit fly embryo

a concentration of bicoid bcd expression in its anterior end

Question 4

organization of mRNAs in maternal cells

Answer 4

organized in cytoplasmic granules with several regulatory proteins responsible for thier post transcriptional processing and thus translational regulation

Question 5

fish and amphibian mRNA structure

Answer 5

fish and amphibians have a large structure knwon and mitochondrial cloud of balbiani body at the vegital pole of the oocyte that consits of mitochondrial and cytoplasmic granules containing silences mRNAs

Question 6

two major control points in euk transltion initiation

Answer 6

supply of eIF2 and supply of eIF4E

Question 7

eEF2 when phosphorylated

Answer 7

beocmes non functional

Question 8

what does phosphorylation of eEF2 lead to

Answer 8

sequestering eIF2B and preventing eIF2B fron acting as a GNEF

Question 9

what phosphorylated eEF2

Answer 9

three protein kinases

GCN2
PKR
PERK

Question 10

GCN2 responds to

Answer 10

response to lower amino acid and glucose sypply in yeast

Question 11

PKRresponds to

Answer 11

responds to viral invasion

Question 12

PERK kinase responds to

Answer 12

responds to unfolded proteins in the cytoplasm

Question 13

what do protein kinases that phosporylate eIF2 resopnd to

Answer 13

conditions in which the cell would want to turn down protein synth

Question 14

why does GCN2 respond to aa supply

Answer 14

lower [aa] means more uncharged tRNA

these bind to GCN2

activating a kinase that phosphorylated eIF2

sequester eIF2B preventing it from acting as a GNEF

depleting supply of eIF2 available to start protein synth

Question 15

eIF4E binding proteins

Answer 15

4E-BP bind and sequester eIF4E to prevent assemly of ribosomal complex

Question 16

phosphorylation of what prevents binding and sequesteriation

Answer 16

phosphorylation of eIF4E and 4E BP

Question 17

phosphorylation in eIF4E favours what

Answer 17

protien synth

Question 18

what genes do we want to keep synthesizing when expressing GCN2

Answer 18

amino acid biosynthesis genes

Question 19

what counters cation of GCN2

Answer 19

GCN4

Question 20

how is GCN4 expression regulated

Answer 20

at the level of translation

Question 21

what does GCN4 do

Answer 21

activataes transcription of aa synth genes in reponse to cellular stvation

Question 22

what does experessoin of GCN4 depend on

Answer 22

translation of small orf upstream of GCN4

Question 23

the sequence context of what favours ribosomes scanning and reinitiation

Answer 23

uORF1 but not uORF2-4

Question 24

why would uORF4 be translated stopping reinitiation

Answer 24

bc you have high AA so AAtRNA can translated it in the non starved state no GCN4

Question 25

regulation fo GCN4 steps

Answer 25

uORF1 alwyas translated which favours rescanning downstream without ribosome reassebly if eIF2 is abundant, uORF2-4 will be translated but their stop codons do not favour further downstream rescanning so translation will stop after one of the next three ORF

Question 26

what happens if eIF2 is not abundant

Answer 26

scannig continues until GCN4 reading frame is reached and GCN4 is translted at high levels

Question 27

viruses and cap dependent initiation

Answer 27

some viruses disrupt cap dependent initiation in order to redirect the host machinery

Question 28

what virus disrupts cap dependent initiation

Answer 28

EMCV- picornavirus dephosphorylated 4E-BP with the result that eIF4E is sequested and host portein synth is reduced

Question 29

what does influenza virus do

Answer 29

produces endonuclease that targets host mRNA but not viral mRNA

Question 30

picornavirus what does it do

Answer 30

poliovirus produce protease that destroys eIF4E and PABP

Question 31

why is iron essential

Answer 31

for ocygen and electron transport

Question 32

why is iron bad

Answer 32

bc it is insoluble and toxic

Question 33

iron storage and uptake

Answer 33

plasma carried by transferrin excess stored by ferritin transferrin receptors import iron by internalixing the transferrin iron complex through receptor mediated endocytosis

Question 34

iron uptake and storage is regulted thorugh tranlstaion by

Answer 34

RNA binding and iron regulatory proteins

Question 35

where do iron regulatory proteins bind

Answer 35

to stem loop structures 5'UTR of the ferritin mRNA 3'UTR of the transferrin receptor mRNA

Question 36

what blocks tranlstion of ferritin mRNA blocked by

Answer 36

empty iron biding proteins which bind to iron response element between cap and the first AUG

Question 37

what happnes if iron is present

Answer 37

ferritin is needed in a hurry iron binds it iron binding portien and ferritin mRNA can be tranlsated