ch 12 Flashcards
translation
mRNA to protein
main component of translation
ribosome tRNA, mRNA,
where do ribosome get assembled
in nucleolus
ribosome main purpose
decode mRNA, catalyze formation of peptide bonds bn amino acids (polypeptide polymerase)
what are ribosome composed of
ribo RNa and ribo porteins
prokaryote rib have - proteins
54
eukaryotic ribosomes have - proteins
82
”s” units
Svedberg unit
equal to 10^-13 seconds durring density gradient centrifugation
shape and size
S increases with
particle mass
small subunit parts
head, base, platform
large unit parts
central protuberance, ridge, stalk
t RNA binding sites
A (acceptor),P(hold peptide),E(exit)
large submit
forms peptide bonds
has peptide transferase center
small subunit
decode mRNA (charged tRNA decode thru codons),
attachment of mRNA for initiation
nucleolus
non membrane bond subcompartment of nucleus
site of 45S preibosomal RNA transcription
nucleolus
45s pre rRNA contains what parts (3) and what is it processed by
28s, 18s, 5.8s
processed by snRNA
5s rRNA is transcribed by
RNA pol III
what subunits make the large part
28, 5.8, 5
what subunits make the small part
18s
what subunit binds to the mRNA first
small
fidelity is dependent on
codon-anticodon recognition
aminoacyl tRNa synthesis
aminoacyl tRNA synthetases
attaches amino acid to tRNA in 2 steps
aminoacyl tRNA synthetases steps
- amino acid reacts with ATP to adenylylate and pyrophosphate is released
- AMP is released and acid is transferred to 3’ end
how is specific amino acyl tRNA so specific
three letter amino acid designation
uncharge tRNA
methionine tRNA
charged tRNA
methionyl-tRNA
aminoacyl tRNA is accurate bc
high fidelity selection
proofreading
kozak consensus sequence
start of translation in euk
first amino acid added In euk translation
methionine
initiation steps
- ternary complex formed and put onto 40s subunit
- loaded of mRNA
3 finding start codon
4 joining units of ribo to make the ribosomes
Teninary complex is made of
Euk initiation factor (eif2)
GTP
Amino acid charged initiator (met tRNA)
Ternary binds to
40s ribo subunit
eIG4E and eIF4G plus extras like eIF4A associate with
5’ cap
It unwinds any secondary structures
43s complex is made once the thingy reads - going along the kozak consensus sequence
AUG
60s can be loaded after
GTP is hydrolysis to gdp and eif5
Maybe fr fr add ts later
Bruh
When 2B is mutated
Loss of white matter- fatal - leukoencephalopathy
elongation starts with
peptide tRNA in ribo p site
how does aminoacyl-tRNA get carried to A site
as part of ternary complex with GTP bound eEF1A
GTP hydrolysis
peptide bond and translocation mediated by
eEF2, needs GTP hydrolysis
peptide bond formation at
base of central protuberance in large ribo unit
what catalyzes peptide formation
ribosomal RNA- forms catalytic center, decoding site, APE site, and interersubunit interface
the ribosome is a
ribozyme
Singal recognition particle (SRP)
binds to peptide and brings it to the ER
After peptide is synthesized it goes from ribosome to
ER lumen
stop codon (mutilple) recognize by
release factor eRF1 in associate with eRF3
eRF1 and eRF3 is released with
GTP hydrolysis
transcriptional and post translational control
control eIF2, blocks ternary complex formation
hypoxia, viola infections, amino cid starvation, heat shock, may trigger
phosphorylation of alpha subunit of eIF2
