Question

During translation initiation in prokaryotes, a GTP molecule is needed for

A. Formation of formyl-met-tRNA

B. Binding of 30S subunit of ribosome with mRNA

C. Association of 30S mRNA with formyl-met-tRNA

D. Association of 50S subunit of ribosome with initiation complex

Answer 1

Hint: The mechanism by which the mRNA codes for a specific protein is known as Translation. The ribosome converts the mRNA produced from DNA into a chain of specific amino acids in the mechanism. This amino acid chain contributes to the synthesis of proteins. In the ribosomes, the entire translation machinery is located.

Complete Answer:

With the binding of IF-1 and IF-3 to the tiny (30S) ribosomal subunit, initiation begins. In the absence of mRNA and formyl-met-tRNA that would result in a non-functional ribosome, their role is to stop the 30S subunit binding to the 50S subunit. Via the Shine-Dalgarno chain, the smaller subunit now binds to the mRNA and then moves 3' along the mRNA until the AUG initiation codon is found. N-formyl methionine charged initiator tRNA and now binds in a complex with IF-2 and GTP (formyl-met-tRNA / IF-2 / GTP). IF-3 has been released and the 30S initiation complex is called the complex of mRNA, formyl-met-tRNA, IF-1, IF-2, and the 30S ribosomal subunit.  The big (50S) ribosomal subunit now binds to form a 70S initiation complex with the release of IF-1 and IF-2 and the hydrolysis of GTP.

Thus, the right option is C.

Note: A larger subunit, as well as a smaller subunit, form the ribosomes. In turn, the larger subunit consists of two tRNA molecules that are positioned close to each other so that peptide bonds can be formed at the cost of adequate energy. The mRNA reaches the smaller subunit maintained by the complementary codon tRNA molecules, which remain in the larger subunit. Therefore, two codons are retained by two tRNA molecules, positioned near each other, and a peptide bond is formed between them. A wide chain of amino acids is synthesized as this process repeats. When it reaches a stop codon, a chain of amino acid is released.