Question

Following is a list of steps for initiating translation. Put them in the correct order.

1. Binding of initiator tRNA to mRNA
2. Binding of large ribosomal subunit to mRNA
3. Binding of small ribosomal subunit to mRNA
4. Binding of tRNA with 2nd amino acid to the A site
5. Formation of covalent bond between methionine and second amino acid
A) 1, 2, 3, 4, 5
B) 1, 3, 2, 4, 5
C) 2, 3, 1, 4, 5
D) 3, 2, 1, 4, 5
E) 3, 1, 2, 4, 5

Answer 1

The correct order for initiation of translation is when the small ribosomal subunit binds to mRNA, followed by the binding of initiator tRNA, then binding of the large ribosomal subunit, after which tRNA with the second amino acid binds to the A site, and finally the peptide bond formation occurs between methionine and the second amino acid.

Step-by-step explanation:

The correct order for initiating translation is as follows:

1. Binding of small ribosomal subunit to mRNA
2. Binding of initiator tRNA to mRNA
3. Binding of large ribosomal subunit to mRNA
4. Binding of tRNA with 2nd amino acid to the A site
5. Formation of covalent bond between methionine and second amino acid

Therefore, the correct answer is E) 3, 1, 2, 4, 5. This process begins when the small ribosomal subunit binds to the mRNA and locates the START codon (AUG). Subsequently, the initiator tRNA carrying methionine binds to the P site on the ribosome. After that, the large ribosomal subunit binds to the complex, setting the stage for the subsequent binding of a second tRNA to the A site and the formation of a peptide bond between methionine and the second amino acid.