Cundliffe 4 tRNA Flashcards
Extended helix:
each stem =fragment of helix
- L shaped in 3D -not ridged = elbow joint
CCA terminus:
amino acid attaches ester linkage, to –OH 80 A’ -> swinging arm .
Anticodon loop:
recognize codon. goes in ribosomal decoding site
Amino acid added to
cognate tRNA e.g. cysteine :
Cys –tRNA cys -> ala –tRNA cys
tRNA carries
what it’s given => emphasis on importance of enzymes. As don’t bind in free solution.
Polarity of tRNA anticodon & mRNA codon
antiparallel tRNA 3’->5’
mRNA 5’->3’
Amino acids are attached to tRNA by
aminoacyl –tRNA synthase (enzyme): crucial role in ensuring the fidelity of gene expression => proof reading control s replication 1x109 would be wasted, each enzyme cognate to A.A. & tRNA.
Actviation of amino acid
process
Aa+ATP +E ←-> [aa-AMP-E] + PPi (inorganic phosphate)
Adding/charging: of tRNA
[aa-AMP-E] + tRNA ←> aa-tRNA +AMP +E
RIBOSOMES size
70S Bacterial: 3x RNA, ~50 proteins, ~ 2MDa
80S Eukaryotic: 4xRNA, ~80 proteins, ~ 4.5 MDa,
S= in ribosomes
sedimentation coefficient (velocity) using centrifuge => particle mass and shape effect sedimentation
Ribosomal SUBUNITS
Prokaryotic: 70S = 50S + 30S
Eukaryotic: 80S = 60S + 40S
(2/3 RNA BY MASS, 1/3 +Small proteins.)
between each processing ribosomes:
Exchange partners
tRNA bridges
2 active sites:
decoding site of 30S
& peptide bond formation site 50S
Water & ribosomes
solvent exclusion
-water would B-bond => no water close to active sites. => H2O free zone by hydrophobic
PT
Peptidyl Transferase Centre: growing peptide exit from subunit interface via tunnel through body of 50S subunit
