Question

translation can be considered to have three phases or steps: initiation, protein synthesis, and termination. Please give a detailed summary of the factors and molecules involved with each step and, where appropriate, compare/contrast the differences between prokaryotic and eukaryotic translation.

Answer 1

Answer and Explanation:

Prokaryotic Translation :

Initiation :

• First amino acid participating is f-methionine.
• Requires three initiation  components are $IF_1$, $IF_2$ and $IF_3$
• Initiation complex framed at Shine-Dalgarno succession of mRNA.
• There is no concept of Kojak rule in prokaryotic.

Protein synthesis :

• Faster process. Adds 20 amino acids per sec.

• mRNA is poly-cistronic.

• Occurs on 70S ribosome.

Termination :After translation, the formyl group of first formylated methionine is removed. Methionine is retained in the polypeptide chain

Eukaryotic Translation :

Initiation :

• First amino acid taking part in translation if methionine.
• Requires a set of eleven initiation factors, named as eIFn.
• Initiation complex formed at 5’ end of mRNA.
• Kojak rule followed

Protein synthesis :

• Slow process. Adds 1 amino acid per second.
• mRNA is mono-cistronic.  
• Occurs on 80S ribosome.

Termination :

Initiating methionine codon is removed from the polypeptide chain.