the process of protein synthesis eukaryotes

Question 1

eukaryotic initiation
uses what
4 points

Answer 1

uses EIF2
40s
methionyl - tRNAi (met)
gtp

Question 2

initiation what happens

5points

Answer 2

EIF2 40s methionyl - tRNAi(met) and gtp bind togther
40s binds to mRNA with EIF4E AND EIF4G
which binds to cap and poly A tail
40s scans for AUG codon
EIFs then dissociate and 60s binds

Question 3

elongation and termination what happens

Answer 3

similar to prokaryotes
however we use eEF1A AND eEF1(A,B,Y,SIGMA)
TERMINATION uses 1 release factor eRF1

Question 4

protein folding
what causes it to fold
4 points

Answer 4

primary protein sequence
n-teminus starts to fold before C is completed
many proteins are post trancriptionally modified
many proteins bind coenzymes (NAD), cofactors (Zn2+) or prosthetic groups (haem)

Question 5

protein targeting to various locations
what are they
4 points

Answer 5

membrane proteins have hydrophobic sequences
proteins for ER golgi lysosomes are synthesised on ribosomes bound to ER and glycosylated
mitochondria, have specific import sequences
nuclear proteins have special import signals NLS

Question 6

2 kinds of NLS

Answer 6

basic, rich in lysine and arginine

non-basic, hnRNPA1 is hybrophobic

Question 7

big proteins need to get into nucleus how

Answer 7

through nuclear pores
transported
uses GTPase ran

Question 8

chaperones

Answer 8

heat shock proteins

prevents interactions between exposed hydrophobic regions

Question 9

PERK what does it do

Answer 9

exists to couple protein folding to protein synthesis

Question 10

role of perk in ER

Answer 10

can elicit ER stress using brefeldin A (blocks protein processing) or
thapsigargin (interferes with ER Ca2+)

Question 11

mitochondrial proteins
key facts
5 points

Answer 11

smaller circular genome
encodes for 13 proteins
ribosomes are smaller
lack of introns
mainly lack non-coding regions UTRs