Cell bio 406 Lecture 4
Card Set Information
Cell bio 406 Lecture 4
What is translation?
process by which proteins are synthesized
Where does translation occur?
Ribosome in the cytoplasm of eukaryotes.
When is transcription coupled with translation?
How many steps does translation occur in?
What is initiation?
Translation machinery recognizes and binds to mRNA.
What is elongation?
Translation machinery add amino acids to the growing polypeptide chain.
What is termination?
Translation machinery stops synthesis and dissociates from mRNA.
What are ribosomes?
A ribosome binds mRNA and tRNA.
It is the structure where translation occurs.
What makes up a ribosome?
ribonucleoprotein (rRNA and protein)
What does anti-shine del garno sequence recognize?
ribosomal binding site (RBS) on mRNA for initiation.
What do eukaryotes have instead of shine del garno sequence?
5' cap for ribosomal recognition.
What links together amino acids during elongation?
peptidyl transferase activity
What carries the amino acids?
What determines amino acid selection?
what is aminoacylation?
process by which aminoacyl tRNA synthetases add amino acids to the acceptor stem of tRNA.
Where does aminoacyl tRNA syntheses add corresponding amino acid?
3' end of the tRNA
what does aminoacyl tRNA synthetase recognize?
how many amino acids per enzyme?
How are unnatural amino acids incorporated?
mutations in enzymes.
what are the different areas in tRNA?
D-loop, anticodon loop, variable loop, tWc loop, acceptor stem.
What ends initiation?
synthesis of the first peptide bond of the polypeptide
Where does ribosomal assembly occur?
in the 5' UTR
What dictates the length of protein?
start and stop codons
Where is the transcription start?
between the 5' cap and the 5' UTR.
Where is the start codon?
Between the 5' UTR and the coding region.
Where is the stop codon?
Between the coding region and the 3' UTR.
Where is the poly (A) signal?
Between the 3'UTR and the poly (A) tail.
What subunit binds to mRNA in bacteria?
30S (16s anti-shine delgarno sequence)
What is required for 30S to bind to mRNA?
Initiation factors 1 and 3.
What do all initation regions have?
two consensus elements.
What are the two consensus sequences in bacteria?
shine-delgarno sequence and AUG.
what is the ribosomal binding site for prokaryotes?
What is the ribosomal binding site in eukaryotes?
Where does the subunit bind to initiate translation in eukaryotes?
Where does subunit migrate after binding to methylated cap?
what is upstream of the initiation site in eukaryotes?
Kozak consensus sequence.
What brings the first tRNA to the first codon AUG in prokaryotes?
IF2, initiation factor 2.
Where does IF 2 bring tRNA in prokaryotes?
to P site.
When can 50s subunit bind?
After IFs are released.
What drive elongation?
Translocation of tRNAs along the different sites of a ribosome.
Where is 1st tRNA placed?
Where does 2nd tRNA enter?
Where does tRNA without an amino acid move to?
Where does the amino acid go when the tRNA moves to the E site?
to the Amino Acid chain
What loads Aminoacyl-tRNA into the A site?
Elongation Factor Tu
What is required for translocation?
What kind of tRNA is in the P site?
What type of tRNA enters A site?
What kind of tRNA moves to E site?
What causes the shift from tRNA binding to translocation?
alternating binding of EF-Tu and EF-G
How does alternating binding of EF-Tu and EF-G cause shift from binding to translocation?
Changing the ribosomal structure
What does peptidyl transferase activity do?
transfers amino acid from tRNA to the polypeptide chain forming peptide bonds.
How many stop codons?
What are the stop codons?
What recognizes termination codons?
protein release factors
What is RF1
bacterial release factor that recognizes UAA and UAG signals to terminate polypeptide translation
What is RF2?
bacterial release factor that recognizes UAA and UGA to terminate translation.
What is RF3?
Removes RF1 and RF2 terminating transcription.
What is RF3 related to?
Who shares genetic code?
smallest bacteria to complex animals
Can genes be transplanted?
yes and become transcribed and translated
What regulates translation in mammalian cells?
What does mTOR-Raptor-GbetaL complex block
Inhibitory effects of 4E-BP1 and S6 kinase
What does mTOR complex with?
GbL and Raptor
What does 4E-BP1 do?
binds with elF4E and blocks its assembly with the 7MeG cap
What does S6K do?
phosphorylates ribosomal protein S6 to inhibit 43S ribosomal preinitiation complex.
Where is mRNA translated?
in specific regions of the cell
How do mRNA deliver proteins to their site of synthesis?
ZBPs zipcode binding proteins
What transports the mRNA to their destination?
motor proteins along the cytoskeletal systems
What leads to cell polarity?
protein asymetric localization
why is asymetric localization important?
It is used to form lamellopodia in migratory cells.
Where do ZBP bind?
in the 3' UTR
what is mRNP
What does mRNP do?
Controls mRNA localization, translation, and turnover