Question

Determine whether the following events occur during initiation, elongation, or termination. This is regarding protein synthesis.

-in E. coli, mRNA binds to the 30S ribosomal subunit

-translocation occurs

-in prokaryotes, the Shine-Dalgarno sequence pairs with rRNA

-initiator tRNA enters the P site

-in E. coli, EF-Tu delivers an aminoacyl-tRNA to the ribosome

-the ribosome has mRNA, an empty A site, and deacylated tRNA in the P site

-in E. coli, EF-Tu hydrolyzes

Answer 1

In E. coli, mRNA binding to the 30S ribosomal subunit occurs during initiation. Translocation occurs during elongation. In prokaryotes, the Shine-Dalgarno sequence pairs with rRNA during initiation.

Step-by-step explanation:

In E. coli, mRNA binding to the 30S ribosomal subunit occurs during initiation of protein synthesis. This binding is part of the formation of the initiation complex. The small 30S ribosome, the mRNA template, and three initiation factors are involved in this process.

Translocation, where the ribosome moves along the mRNA template, occurs during the elongation phase of protein synthesis. This step allows the tRNA with the growing polypeptide chain to move from the A site to the P site on the ribosome.

In prokaryotes, the Shine-Dalgarno sequence pairs with rRNA during initiation. This interaction helps position the mRNA on the ribosome and is unique to prokaryotes.

Answer 2

The provided events can be classified as:

Initiation

• In prokaryotes, the Shine-Dalgarno sequence pairs with rRNA.
• In E. coli, mRNA binds to the 30S ribosomal subunit.

Elongation

• In E. coli, EF-Tu delivers an aminoacyl-tRNA to the ribosome
• Initiator tRNA enters the P site.
• In E. coli, EF-Tu hydrolyzes.
• Translocation occurs

Termination

• The ribosome has mRNA, an empty A site, and deacylated tRNA in the P site

Translation is the process by which polypeptide chain is synthesized based on the codon sequence of the mRNA (messenger ribonucleic acid).

It is divided into three stages:

Initiation: The small and large sub-units of the ribosome get assembled around the initiation codon. It forms three sites (A, P, and E site) for interaction tRNA and mRNA.

Elongation: Specific charged-tRNA enters from A site and transfers its amino acid to the growing polypeptide chain in P site. Uncharged tRNA exit from the E site. Ribosome moves or translocates to the next codon.

Termination: As soon as ribosome reaches the termination codon, it releases the newly synthesized polypeptide chain.