The document summarizes the process of translation in eukaryotes. It describes how amino acids are activated and attached to specific tRNAs. Then it explains the initiation, elongation, and termination steps of translation. In initiation, a preinitiation complex forms on the 5' end of mRNA. In elongation, aminoacyl-tRNAs bring amino acids to the ribosome in sequence to elongate the polypeptide chain. Termination occurs when release factors recognize a stop codon and catalyze protein release from the ribosome.

1. Translation in Eukaryatic
During the translation process
proteins are made by the ribosomes
on the mRNA strand.

2. The main steps
• Activation of amino acid.
• Transfer of amino acid to tRNA.
• Initiation of synthesis.
• Elongation of polypeptide chain.
• Chain termination.

3. Activation of aminoacid
• Amionacid + ATP + Aminoacyl tRNA
synthetase→→→ Aminoacyl adenylate
synthetase + Inorganic Pyrophosphate.

4. Activation of aminoacid

5. • The activated aminoacid is transferred to its
specific tRNA.
• A high-energy ester bond is formed between
the carboxyl group of the amino acid and the
3’- hydroxy group of the terminal adenosine of
tRNA.
• The aminoacyl adenylate, which is attached
to the activating enzyme, reacts with a specific
tRNA to from an aminoacyl-tRNA complex.

6. • The synthetase thus has two active sites, one for
recognizing the specific amino acid and the other
for recognizing the specific tRNA molecule.
• It functions in bringing the amino acid molecule
and its specific tRNA together.
• Similarly the tRNA molecule has two selection
sites, one for recognizing its specific aminoacyl
tRNA synthetase and the other, the anticodon, for
recognizing the codon on mRNA.

7. Chain initiation

8. In eukaryotes, eIF3 associates
with the small 40S subunit, and
eIF6 binds to the large 60S
subunit.
The first step of translation
initiation is formation of a
preinitiation complex.
It is formed by association of 40S
subunit with eIF3 complex
associate with eIF1A and a Met-
tRNAᵢ ᴹᵉᵗ and eIF2 bound to GTP.
The 5’ cap of an mRNA to be
translated is bound by the eIF4
cap- binding complex.
• The eIF4 consist of many sub
un its--- eIF4E subunits binds
the 5’cap structure on mRNAs.
• The mRNA-eIF4 complex then
associates with the
preinitiation complex through
eIF4G subunit with eIF3 in the
preinitiation complex ,
forming the initiation complex.
• The helicase activity of eIF4B
subunit scan, unwind s the
RNA secondary structure .
• Scanning stops when the
tRNAᵢᴹᵉᵗ anticodon recognizes
the start codon.

10. • Once correctly positioned,
• the GTP bound eIf2 is hydrolyzed to GDP,
eIF1,2,3,and4 dissociate and the small subunit
unites with large subunit 60S in a process
catalyzed by eIF5 and 6, completing formation
of 80S ribosome.
• The large subunit recruitment accompanied
with hydrolysis of a GTP bound by eIF5.

11. Chain Elongation

12. • Now the complex is ready to the stepwise
addition of amino acid by in frame translation
of the mRNA.
• The second aminoacyl tRNA is brought into
the ribosome with EF1α.GTP and become
bound to the A site. When that occurs
properly GTP in the associated EF1α.GTP is
hydrolyzed and release of the resulting EFα.
GDP complex.

13. • With the in initiating Met-tRNAᵢᴹᵉᵗat the p site
and the second aminoacyl-tRNA tightly bound
at the A site,
• the α amino group of the second amino acid
react with the “activated” methionine on the
initiator tRNA forming a peptide bond
catalyzed by peptidyltransferase.

15. • Following peptide bond formation, the ribosome
translocation along with mRNA a distance equal
to one codon.
• Once has occurred correctly EF2 bound GTP
hydrolyzed, tRNAᵢᴹᵉᵗ, now without its activated
methionine, is moved to the E site on the
ribosome ;
• concurrently, the second tRNA, now covalently
bound to a dipeptide , is moved to the P site.
Now the A site is open and able to accept
another aminoacid , the cycle is repeated.

16. Chain termination

17. • Eukaryotic eRF1, bind to the ribosomal A site
and recognizing stop codons directly. The
second release factor, eRF3, is a GTP-binding
protein.
• The eRF3-GTP acts in concert with eRF1 to
promote cleavage of the peptidyl-tRNA, thus
releasing the completed protein chain.