Question

How does the eukaryotic initiation complex locate the correct start codon?

A) The true start codon is the first ATG encountered downstream of the Shine-Dalgarno sequence.
B) The initiation complex moves the small ribosomal subunit through the 5ʹ UTR, scanning for the start AUG.
C) The pre-initiation complex moves the ribosome through the 3ʹ UTR, scanning for the Kozak sequence.
D) The correct start codon is the first ATG encountered downstream of the Kozak sequence.
E) The correct start codon is the formyl-ATG, which will encode for fMet in the protein.

Answer 1

The correct answer will be option-C

Step-by-step explanation:

The eukaryotic translation takes place in three steps that are initiation, elongation and termination.

During the initiation process, the amino-acyl tRNA carrying the methionine amino acid binds the small ribosomal subunit. This pre-initiation complex of small subunit and tRNA now gets attached to 5ʹ UTR and starts scanning mRNA to find start codon -AUG.

The pre-initiation complex when finds the start codon attaches the large subunit of ribosome and form initiation complex. The formation of the initiation complex begins the process of translation.

Thus, Option-C is the correct answer.