Question

Which amino acid is the universal initiator for protein synthesis in eukaryotes?

• A. Methionine
• B. Valine
• C. Leucine
• D. Alanine

Hint:

{Start Codon (AUG) → Methionine}.
In prokaryotes: (fMet) (formyl-methionine).
In eukaryotes: Methionine.

Answer 1

The Correct Option is A

Concept: Protein synthesis (translation) begins with a specific initiator amino acid that is incorporated into the first position of the growing polypeptide chain. The initiator amino acid is delivered by a specialized initiator tRNA that recognizes the start codon on mRNA.
Step 1:Start codon in translation.
The process of translation typically begins at the start codon: [ AUG ] This codon signals the ribosome to begin protein synthesis.
Step 2:Initiator amino acid in eukaryotes.
In eukaryotic cells, the codon (AUG) codes for the amino acid methionine. A special initiator tRNA carrying methionine recognizes this start codon and binds to the ribosome to initiate translation.
Step 3:Difference between prokaryotes and eukaryotes.
Although methionine is also the starting amino acid in prokaryotes, it is modified into N-formylmethionine (fMet) in bacteria. Thus, the universal initiator amino acid for protein synthesis in eukaryotes is methionine.