Eukaryotic Translation

Question 1

How many S has each subunit of eukaryotic ribosome and how many has the whole ribosome?

Answer 1

40S - small
60S -large
80S - Ribosome

Question 2

At what sequence does the ribosome assemble for translation?

Answer 2

Kozak sequence

Question 3

What are the steps for translation initiation?

Answer 3

1) elF2 ternary complex formation
2) 43S complex formation
3) mRNA activation by elF4 complex + 4B
4) 43S complex attaches to mRNA
5) 5’-3’ scanning
6) Initiation codon recognition, hydrolysis of elF2-bound GTP and Pi release
7) Binding of large subunit and release of almost all initation factors
8) Hydrolysis of 5B-bound GTP and release of 5B and 1A

Question 4

How is GTP used during the translation process?

Answer 4

2 GTP molecules are used per each added AA. 1st, the GTP hydrolysis allows for the confirmational change on ribosome that brings the AAs from side A and P close together. 2nd GTP molecule is used for RIbosome translocation after the peptide bond has been formed.

Question 5

How is translation terminated?

Answer 5

• RF1 and associated RF3-GTP binds to stop codon in the A site
• Complete polypeptide is cut off from the tRNA and released
• Ribosome dissociates and its elements are recycled for future use