Part A Place the following steps for the initiation of bacterial protein biosynt

Question

Part A

Place the following steps for the initiation of bacterial protein biosynthesis in the correct order:

1) simultaneous binding of mRNA
2) Initiating factor 2 (IF2) with bound GTP delivers fMet-tRNA.
3) reassociation of the 50S subunit
4) binding of IF1 and IF3 to the 30S subunit that promotes the dissociation of the ribosome into the 30S and 50S subunits
5) release of IF3
6) GTP hydrolysis to GDP, IF1, IF2, and Pi release
7) The AUG initiation codon binds in the P site.

Place the following steps for the initiation of bacterial protein biosynthesis in the correct order:

1) simultaneous binding of mRNA
2) Initiating factor 2 (IF2) with bound GTP delivers fMet-tRNA.
3) reassociation of the 50S subunit
4) binding of IF1 and IF3 to the 30S subunit that promotes the dissociation of the ribosome into the 30S and 50S subunits
5) release of IF3
6) GTP hydrolysis to GDP, IF1, IF2, and Pi release
7) The AUG initiation codon binds in the P site.

Explanation / Answer

The correct sequence is:

4,2,1,3,5,7,6

Reason: Binding of IF1 and IF3 to 30S subunit that dissoaciates ribosomes and initiates translation.IF1 binds to A A site of 30 S subunit so as to direct the delivery of f-Met-tRNA to P site of 30 S subunit by blocking the A site.Next binding of mRNA occurs.50 S subunit joins next.By this time IF3 is released and AUG codon binds to Psite.IF1 ,IF2 are released from the complex by GTP hydrolysis.(Pi is released).

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