7-translation Flashcards
Where does ribosome bind to in prokaryotes?
Shine Dalgarno sequences
Where does SSU of ribosome bind in eukaryotes?
5’cap
What is the difference between the 5’ cap and Kozac sequence?
the 5’ cap is the ribosomal binding site whereas the Kozac sequence is recognised by the ribosome as translational start site
what is a ribosome and what activity does it have?
a ribonucleoprotein with ribozymal activity
what is the difference between the tRNA in prokayotes and eukaryotes?
in eukaryotes it is tRNA methionine whereas in prokaryotes it is tRNA formylmethionine
what kind of activity takes place at ribosome?
peptidyl transferase activity
what to prokaryote IF 1 and 3 do?
stop LSU binding before initiation is complete
what does prokaryotic IF2 do?
bring tRNA formylmet to initiation complex
what doe eIF1 do?
blocks A site
what does eIF2 do?
brings tRNA to P site
what does eIF3 do?
stops LSU binding before initiation is complete
what occupies P site?
tRNA
What is GTP needed for?
the transfer of peptidyl on P site tRNA to A site tRNA aminocyl
what is bound to GTP?
eIF2
what does peptidyl transferase help form?
a peptide bond between the 2 amino acids
what does tRNA deacylase do?
breaks bond berween methionine and it tRNA
what does EF1 do?
helps entry of tRNA to A site
what does EF2 do?
translocates ribosome (shunts it along)
what happens in the LSU?
catalysis of peptide bond formation
what happens when termination codon enters a site?
termination
how many sites are there and what are they in ribosomes?
3: E,P,A
how many release factors are there in e.coli?
3 RF:1,2,3
what do release factors cause?
termination
how many release factors do eukaryotes have?
1 (eRF)
What are release factors?
tRNA peptidyl hydrolases
what happens at termination to the ribosome and mRNA?
ribosome dissociates and the mRNA is released.
what is cystic fibrosis due to?
misfolding of transmembrane regulator
what disease is caused by the misfolding of fibrillin?
Marfan syndrome
what disease is caused by a change to a prion protein and what change is it?
Creutzfeld Jakob disease caused by prion extra-cellular aggreggation
Why is extra cellular aggregation of beta amyloid bad?
causes alzheimers disease
what happens at barrel of GRoel/GroES chaperon?
folding aided (Heat shock protein)
where does folding take place in chaperones?
in barrel of GroEL/GroEs
what is the 5’ ubiquitin tail added to in degradation of proteins process?
lysine of waste protein
outline the steps of protein degradation (3)
5’ ubiquitin tail added to lysin of waste protein. regulatory subunit recognises this and protein is deubiquinated and unfolded. Finally proteolytic enzymes degrade the protein
What 2 things do regulatory subunits do in protein degradation?
de ubiquinate 5’ubiquitin tail and unfold waste protein
what is protein folding primarily determined by?
primary structure
what does EIF4 do?
untangles mRNA
what do we mean by the genetic code is degenerate?
more than one codon codes for same amino acid
how many tRNAs are there in comparison to possible codons?
around 40 tRNAs but 64 codons
what does wobble mean and 3’ base degeneracy mean?
tRNAs can recognise more that one codon as anticodon can bind to alternative bases at 3rd position. This decreases amount of tRNAs required.
What can inosine base pair with?
C,A,U
what is inosine?
deaminated form of guanine
what can g pase pair with when it is at 3rd position in anticodon?
U and C
why can variation of anticodon be tolerated (wobble) ?
anticodon loop is not linear and when anticodon binds to codon does not form a perfect RNA double helix.
what does polycistronic mean?
a single mRNA encoding several different polypeptide chains
do eukaryotes have polycistronic mRNA?
No they have monocistronic
what are isoacceptors?
tRNAs that bind the same amino acid
what is aminoacy-tRNA? and what does it deliver to the ribosome?
Aminoacyl-tRNA is tRNA to which its cognated amino acid is chemically bonded. The aa-tRNA with elongation factors, deliver the amino acid to the ribosome for incorporation into the polypeptide chain.
what processes need GTP?
ribosome movement and binding of accessory factors
what processes need ATP?
charging of tRNAs and removal of secondary structure from mRNA
