Translation

Wobble occurs

Wobble occurs

________ in the tRNA anti- codon: 3rd base is less constrained and pairs less specifically.

Release factors

________ (RFs) bind to stop codon and assist the ribosome in terminating translation.

Eukaryote AUG codon

________ is embedded in a short initiation sequence called the Kozak sequence.

Code is non-overlapping

each nucleotide is part of only one codon and is read only once

Code is almost universal

most codons have the same meaning in different organisms

Code is degenerate

18 of 20 amino acids are coded by more than one codon

Code has start and stop signals

AUG codes for Met and is the usual start signal

Wobble occurs in the tRNA anti-codon

3rd base is less constrained and pairs less specifically

P site

peptidyl site

A site

aminoacyl site

E site

exit site

Initiation

a functionally competent ribosome is assembled in the correct place on the mRNA and ready to start protein synthesis

Elongation

tRNA brings the correct amino acid to the ribosome,  it is joined to the nascent polypeptide chain and the entire assembly moves to the next triplet along the mRNA

Termination

a stop codon is reached and the entire assembly dissociates to release the newly-synthesized polypeptide

Initiation factor (IF

4F) binds to the 5 cap on the mature mRNA

IF 1

associates with 30S subunit in the A site 🡪 preventing a tRNA from entering

IF 3

allows for 30S subunit to bind to specific site of mRNA, checks for accuracy of binding of first aa tRNA

IF 2-GTP

binds to 30S P site upon which fmet-tRNA binds to IF2 and IF2 moves it to P site

Peptidyl transferase (catalytic RNA molecule

ribozyme) forms a peptide bond between the free amino acid in the P site and aminoacyl-tRNA in the A site